Enzio Ragg - Academia.edu (original) (raw)
Papers by Enzio Ragg
Bioorganic & Medicinal Chemistry Letters, 1997
The design, synthesis, in vitro and in vivo activities of novel benzoyl and cinnamoyl nitrogen mu... more The design, synthesis, in vitro and in vivo activities of novel benzoyl and cinnamoyl nitrogen mustard and half-mustard derivatives of distamycin A are described and structure-activity relationships are discussed. The equipotent activities of N-ethyl-N-chloroethyl half-mustards and N,N-dichloroethyl mustards and the superior activities of cinnamoyl derivatives are the most relevant features of the series.
Journal of the Chemical Society, Perkin Transactions 1, 1993
... Anna Arnoldi," Angela Bassoli, Lucio Merlini and Enzio Ragg Dipartimento di Scienze Mole... more ... Anna Arnoldi," Angela Bassoli, Lucio Merlini and Enzio Ragg Dipartimento di Scienze Molecolari Agroaiimentari, Sezione di Chimica, Universita di Milano, via Celoria 2 ... Lindley and Shallenberger ' attempted to explain the effect in the case of 5-thio-PD-glucose and 6-thio-P ...
Brostallicin (PNU-166196) is a synthetic -bromoacrylic, second- generation DNA minor groove binde... more Brostallicin (PNU-166196) is a synthetic -bromoacrylic, second- generation DNA minor groove binder structurally related to distamycin A, presently in Phase II trials in Europe and the United States. The compound shows broad antitumor activity in preclinical models and dramatically reduced in vitro myelotoxicity in human hematopoietic pro- genitor cells compared with that of other minor groove binders. Brostal- licin showed
Physiologia Plantarum, 1995
... 1995 Capynglu © Flr^,loi;ia Flanlar^,,, IW5 f'nnU'iI in ih&... more ... 1995 Capynglu © Flr^,loi;ia Flanlar^,,, IW5 f'nnU'iI in ih'tiinarL - ii!ln^fi!\ reservi-d Germination and pH of intracellular compartments in seeds of PhaceUa tanacetifolia Luca Espen, Silvia Morgutti, Chiara Alisi, Livia Pirovano, Enzio Ragg and Sergio M. Cocucci Espen. ...
Journal of Molecular Biology, 2000
Prion diseases are characterized by the accumulation of altered forms of the prion protein (terme... more Prion diseases are characterized by the accumulation of altered forms of the prion protein (termed PrP Sc ) in the brain. Unlike the normal protein, PrP Sc isoforms have a high content of b-sheet secondary structure, are protease-resistant, and form insoluble aggregates and amyloid ®brils. Evidence indicates that they are responsible for neuropathological changes (i.e. nerve cell degeneration and glial cell activation) and transmissibility of the disease process. Here, we show that the antibiotic tetracycline: (i) binds to amyloid ®brils generated by synthetic peptides corresponding to residues 106-126 and 82-146 of human PrP; (ii) hinders assembly of these peptides into amyloid ®brils; (iii) reverts the protease resistance of PrP peptide aggregates and PrP Sc extracted from brain tissue of patients with Creutzfeldt-Jakob disease; (iv) prevents neuronal death and astrocyte proliferation induced by PrP peptides in vitro. NMR spectroscopy revealed several through-space interactions between aromatic protons of tetracycline and side-chain protons of Ala 117-119 , Val 121-122 and Leu 125 of PrP 106-126. These properties make tetracycline a prototype of compounds with the potential of inactivating the pathogenic forms of PrP.
Bioorganic & Medicinal Chemistry Letters, 2000
AbstractÐThe design, synthesis, and cytotoxic activity of novel benzoyl and cinnamoyl sulfur must... more AbstractÐThe design, synthesis, and cytotoxic activity of novel benzoyl and cinnamoyl sulfur mustard derivatives of distamycin A are described and structure±activity relationships are discussed. These sulfur mustards are more potent cytotoxics than corresponding nitrogen mustards in spite of the lower alkylating power, while their sulfoxide analogues are substantially inactive. Cinnamoyl sulfur mustard derivative proved to be one of the most active distamycin-derived cytotoxics, about 1000 times more potent than melphalan. #
European Journal of Biochemistry, 1994
The aggregative properties of GalNAc-G,,, ganglioside, in comparison with those of G,,,, have bee... more The aggregative properties of GalNAc-G,,, ganglioside, in comparison with those of G,,,, have been investigated and correlated to the intrinsic conformation and mobility of the oligosaccharide chain of the molecules. Micellar parameters in aqueous solution (molecular mass, hydrodynamic radius as well as the surface area at the lipidwater interface and the packing parameter of the monomer inserted in the aggregate) are measured by the laser light-scattering technique. The presence of a further GalNAc residue causes a 22% increase in molecular mass, contrary to expectation. Oligosaccharide moiety three-dimensional structures have been modeled using molecular mechanics and dynamics calculations, based on NOE interactions observed for native gangliosides dissolved in deuterated dimethylsulfoxide or, as mixed micelles with fully deuterated dodecylphosphocholine, in D,O. Compared with G,,, the GalNAc-G,,, is less mobile, thus influencing the surface area, this lower mobility together with the GalNAc-G,,, conformation leads to a larger number of monomers participating in the formation of the micelle. The results further substantiate the model in which the three-dimensional structure and the intrinsic dynamic properties of the oligosaccharide chain affect the geometrical properties of the aggregate. Gangliosides, glycosphingolipids characterized by the presence of sialic acid residue(s) (Wiegandt, 1985), are components of vertebrate cell plasma membrane where they play an important role in a variety of surface events such as recog-Correspondence to S. Sonnino, Dipartimento di Chimica e Fax: +39 2 2363584. Abbreviations. Ganglioside nomenclature is in accordance with Svennerholm (1 980) and the IUPAC-IUB recommendations (1 977, 1982). G,,, 13NeuSAcGalCer, a-NeuSAc-(2-3)-P-Gal-(l-l)-Cer; G,,, I13Neu5AcLacCer, a-NeuSAc-(2-3)-P-Gal-(1-4)-~-Glc-(l-l)-Cer; G,,, I13Neu5AcGgOse,Cer, P-GalNAc-(1-4)-[a-Neu5Ac-(2-3)]-~-Gal-(1-4)-j-Glc-(l-l)-Cer ; G,,, I13NeuSAcGgOse,Cer, P-Gal-(1 -3)-P-GalNAc-( 1-4)-[a-NeuSAc-(2-3)] +Gal-( 1-4)-j?-Glc-(I-l)-Cer; G,,,,, I13Neu5AcGgOse,, P-Ga1-(1-3)-j-GalNAc-(1-4)-[a-NeuSAc-( 2-3)]-b-Gal-( 1 -4)-Glc ; G,,,, IV3NeuSAcI13Neu5AcGg-Ose,Cer, cr-NeuSAc-(2-3)-,8-Gal-( 1 -3)-/7-GalNAc-( 1 -4)-[a-NeuSAc-(2-3)]-P-Gal-( 1 -4)-P-Glc-( 1-1)-Cer ; G,,,,,, IV3NeuSAcI13NeuS-AcGgOse,, a-NeuSAc-(2-3)-P-Gal-(1-3)-P-CalNAc-(1-4)-[a-Neu5-Ac-(2-3)]-P-Gal-(1-4)-Glc ; GalNAc-G,,,, IV4GalNAcIV3-Neu5-AcI13Neu5AcGgOse,Cer, P-GalNAc-(1-4)-[a-NeuSAc-(2-3)]-P-Gal-(
Phytochemistry, 1995
A new derivative of pantoic acid, R( - ) pantoyllactone-β-d glucopyranoside, has been isolated fr... more A new derivative of pantoic acid, R( - ) pantoyllactone-β-d glucopyranoside, has been isolated from rice seedlings and its structure determined. β-Glucosidase hydrolysed it to d-glucose and R( - )pantoyllactone. Alkaline hydrolysis converted it to the salt of 2-R( - )pantoic acid β-d-glucopyranoside. It accumulated in rice shoots but not in roots.
Journal of the Chemical Society, Perkin Transactions 2, 1997
... Stefania Mazzini,a Lucio Merlini,a Rosanna Mondelli,*,a Gianluca Nasini,b Enzio Ragga andLeon... more ... Stefania Mazzini,a Lucio Merlini,a Rosanna Mondelli,*,a Gianluca Nasini,b Enzio Ragga andLeonardo Scaglionia a Dipartimento di Scienze Molecolari Agrolimentari, Sezione di Chimica, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy b Centro del CNR per ...
Steroids, 2006
An improved procedure for the microbial hydroxylations of dehydroepiandrosterone (DHEA, 1) and 15... more An improved procedure for the microbial hydroxylations of dehydroepiandrosterone (DHEA, 1) and 15β,16β-methylene-dehydroepiandrosterone (2) was studied using whole cells of Botryodiplodia malorum and Colletotrichum lini. C. lini catalyzed 7α- and 15α-hydroxylation of 1 and 7α-hydroxylation of 2, while B. malorum gave 7β-hydroxylation of both the substrates. The stability of the enzymatic activity was higher in the presence of co-substrates (i.e.,
European Journal of Biochemistry, 1999
Experimental two-dimensional 1 H NMR data have been obtained for PrP106±128 under the following s... more Experimental two-dimensional 1 H NMR data have been obtained for PrP106±128 under the following solvent conditions: deionized water/2,2,2-trifluoroethanol 50 : 50 (v/v) and dimethylsulfoxide. These data were analyzed by restrained molecular mechanics calculations to determine how changes in solvation affect the conformation of the peptide. In deionized water at pH 3.5, the peptide adopted a helical conformation in the hydrophobic region spanning residues Met112±Leu125, with the most populated helical region corresponding to the Ala115±Ala119 segment (< 10%). In trifluoroethanol/H 2 O, the a-helix increased in population especially in the Gly119±Val122 tract (< 25%). The conformation of this region was found to be remarkably sensitive to pH, as the Ala120±Gly124 tract shifted to an extended conformation at pH 7. In dimethylsulfoxide, the hydrophobic cluster adopted a prevalently extended conformation. For all tested solvents the region spanning residues Asn108±Met112 was present in a`turn-like' conformation and included His111, situated just before the starting point of the a-helix. Rather than by conformational changes, the effect of His111 is exerted by changes in its hydrophobicity, triggering aggregation. The amphiphilic properties and the pH-dependent ionizable side-chain of His111 may thus be important for the modulation of the conformational mobility and heterogeneity of PrP106±126.
Journal of the Chemical Society, Perkin Transactions 2, 1993
ABSTRACT The keto–enol tautomerism of the dihydroxyperylenequinone system of a number of natural ... more ABSTRACT The keto–enol tautomerism of the dihydroxyperylenequinone system of a number of natural compounds, cercosporin 1, isocercosporin 2, phleichrome 3, isophleichrome 4, elsinochromes 5–9, cladochrome C 10, and hypocrellin 11 was studied by 1H, 2H and 13C NMR spectroscopy. 4,9-Dihydroxyperylene-3,10-dione and 3,10-dihydroxyperylene-4,9-dione tautomers were recognized as present in fast equilibrium in CDCl3 and [2H6]acetone solutions. The populations of each tautomer were obtained from the coupling between the proton of the hydrogen-bonded OH groups and the adjacent carbon atoms, i.e. J(C3, OH) and J(C4, OH). The most important factors governing the tautomeric equilibrium in these helix-shaped compounds appeared to be the substituent effects, the strength of the intramolecular phenol–quinone hydrogen bond, the distortion from the planarity of the perylenequinone system, solvation and aggregation effects. The strength of the hydrogen bonds, which is related to the distortion from planarity, was evaluated from 1H chemical shifts and primary deuterium isotope effects. Proton shifts of OH groups and isotope effects are linearly correlated. The influence of solvents and concentration on the tautomeric equilibrium was studied in the case of 4, for which a model of vertical stacking-type dimerisation is proposed.
Acta Chemica Scandinavica, 1986
The 1H NMR spectra of carp parvalbumin saturated with Ca2+, Cd2+, La3+ and Lu3+ were compared, us... more The 1H NMR spectra of carp parvalbumin saturated with Ca2+, Cd2+, La3+ and Lu3+ were compared, using 2D 1H NMR techniques as well as conventional 1H NMR spectra. The Ca2+ and Cd2+ saturated parvalbumin (with both high affinity Ca2+-binding sites occupied) gave rise to very similar spectra. This shows that these two species have almost identical protein conformations. The 1H NMR spectrum from the Ln3+ saturated parvalbumins deviated from the other two and it was therefore concluded that Cd2+ is a better probe for Ca2+ than Ln3+ in parvalbumin and probably also for related calcium binding proteins. The addition of excess of divalent metal ions, such as Mg2+ or Ca2+, causes small changes in the chemical shift of some methyl resonances. This is presumably caused by binding of these metal ions to a third site close to the CD site which is made up of the carboxylic groups from Glu 60 and Asp 61.
Environmental Biosafety Research, 2008
The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil b... more The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil bacterial community structure, and their potential to support horizontal gene transfer (HGT) to bacteria have been studied. Soil microcosms were exposed to root-released compounds collected from transplastomic and non-transgenic tobacco cultivars. Cluster analysis of automated ribosomal intergenic spacer analysis (ARISA) profiles of the soil bacterial community after 48 h incubation grouped the transgenic cultivar apart from the non-transgenic, indicating that it had a rhizodeposition pattern different from the parental plants. However, these differences were less than between the two non-transgenic tobacco cultivars studied. NMR characterization of the rootreleased compounds showed some differences in chemical fingerprinting pattern between the transplastomic and the parental cultivar. However, the effect on bacterial community structure was transient, and tended to disappear after 96 h of incubation. The potential of root-released compounds as a source of transforming DNA for bacteria was investigated by using four potential recipient species. No transformants were obtained following exposure of all the recipients to the root-released compounds. Root-released compounds amended to transgene donor DNA decreased the transformation frequency of Acinetobacter baylyi strain ADP1200, while Azospirillum, Agrobacterium, and Sinorhizobium strains failed to develop competence also in the presence of an external added transgene source. Detection of plastid sequences by PCR suggested that a very low amount of fragmented plastid donor DNA was present in the root-released compounds.
FEBS Journal, 2006
Bowman-Birk serine protease inhibitors are a family of small plant proteins, whose physiological ... more Bowman-Birk serine protease inhibitors are a family of small plant proteins, whose physiological role has not been ascertained as yet, while chemopreventive anticarcinogenic properties have repeatedly been claimed. In this work we present data on the isolation of a lentil (Lens culinaris, L., var. Macrosperma) seed trypsin inhibitor (LCTI) and its functional and structural characterization. LCTI is a 7448 Da double-headed trypsin/chymotrypsin inhibitor with dissociation constants equal to 0.54 nM and 7.25 nM for the two proteases, respectively. The inhibitor is, however, hydrolysed by trypsin in a few minutes timescale, leading to a dramatic loss of its affinity for the enzyme. This is due to a substantial difference in the kon and k*on values (1.1 microM-1.s-1 vs. 0.002 microM-1.s-1), respectively, for the intact and modified inhibitor. A similar behaviour was not observed with chymotrypsin. The twenty best NMR structures concurrently showed a canonical Bowman-Birk inhibitor (BBI) conformation with two antipodal beta-hairpins containing the inhibitory domains. The tertiary structure is stabilized by ion pairs and hydrogen bonds involving the side chain and backbone of Asp10-Asp26-Arg28 and Asp36-Asp52 residues. At physiological pH, the final structure results in an asymmetric distribution of opposite charges with a negative electrostatic potential, centred on the C-terminus, and a highly positive potential, surrounding the antitryptic domain. The segment 53-55 lacks the anchoring capacity found in analogous BBIs, thus rendering the protein susceptible to hydrolysis. The inhibitory properties of LCTI, related to the simultaneous presence of two key amino acids (Gln18 and His54), render the molecule unusual within the natural Bowman-Birk inhibitor family.
![Research paper thumbnail of Reversible, Non-Denaturing Metal Substitution in Bovine Adrenodoxin and Spinach Ferredoxin and the Different Reactivities of [2Fe-2S]-Cluster-Containing Proteins](https://attachments.academia-assets.com/45207881/thumbnails/1.jpg)
](European Journal of Biochemistry, 1996
The non-denaturing substitution of cluster iron by other metals was studied in spinach ferredoxin... more The non-denaturing substitution of cluster iron by other metals was studied in spinach ferredoxin and in bovine adrenodoxin. Only some of several metal species tested (Cd", Znz+, VO", Mnz+, Co2+, Ni") caused bleaching of the residual visible absorbance and of the EPR signals of the reduced ferredoxins. No formation of mixed-metal cluster was observed. The most reactive metal species were Cd2+ and Zn2+, and CdZi was found to react also with oxidized adrenodoxin. Metal-treated proteins were resolved into a mixture of apoprotein, metal-substituted protein and unreacted holoprotein. Their biological activity was proportional to the residual holoprotein concentration. Spinach ferredoxin and adrenodoxin were found to differ substantially with regard to their metal-substitution reactivity under oxidizing and reducing conditions, reaction time, and formation of apoprotein, which was more pronounced for spinach ferredoxin. Exchange of cluster iron with Cd" in adrenodoxin generated stable species containing 2 mol sulfide/mol protein, and 2 or 5 mol cadmiudmol protein, respectively. The relative amount of the two substitution products depended on the experimental conditions. CD and NMR data on all the cadmiumsubstituted proteins suggest that iron replacement led to a significant structural rearrangement. Nevertheless, all the metal-substituted proteins could be re-converted into the native iron-containing form upon incubation with iron in the absence of reductants, of denaturing agents, and of an external source of sulfide. The different reactivity of the two proteins is discussed in terms of the cluster environment, along with the possible physiological relevance of these findings.
Tetrahedron, 2000
Novel hybrid porphyrins bearing two and four suitably protected glycosidic units appended at the ... more Novel hybrid porphyrins bearing two and four suitably protected glycosidic units appended at the meso positions of the central macrocycle through robust carboncarbon bonds have been constructed and characterized. Metallation of these constructs with certain bivalent metal ...
PLOS One, 2010
An understanding of the integrated relationships among the principal cellular functions that gove... more An understanding of the integrated relationships among the principal cellular functions that govern the bioenergetic reactions of an organism is necessary to determine how cells remain viable and optimise their fitness in the environment. Urease is a complex enzyme that catalyzes the hydrolysis of urea to ammonia and carbonic acid. While the induction of urease activity by several microorganisms has
Physiologia Plantarum, 1992
Menegus, F, Cattarazza, L., Scaglioni, L. and Ragg, E. 1992. Effects of oxygen level on metabolis... more Menegus, F, Cattarazza, L., Scaglioni, L. and Ragg, E. 1992. Effects of oxygen level on metabolism and development of seedlings of Trapa natans and two ecologically related spedes. -Physioi. Plant. 86; 168-172.
The Journal of Organic Chemistry, 1995
... Sergio Riva and Anna Bertinotti CNR, Istituto di Chimica degli Ormoni, Via Mario Bianco 9, 2... more ... Sergio Riva and Anna Bertinotti CNR, Istituto di Chimica degli Ormoni, Via Mario Bianco 9, 20131 Milano, Italy Enzio Ragg and Leonard0 Scaglioni ... (4) (a) Danieli, B.; De Bellis, P.; Carrea, G.; Riva, S. Heterocycles 1989,29, 2061. ...
Bioorganic & Medicinal Chemistry Letters, 1997
The design, synthesis, in vitro and in vivo activities of novel benzoyl and cinnamoyl nitrogen mu... more The design, synthesis, in vitro and in vivo activities of novel benzoyl and cinnamoyl nitrogen mustard and half-mustard derivatives of distamycin A are described and structure-activity relationships are discussed. The equipotent activities of N-ethyl-N-chloroethyl half-mustards and N,N-dichloroethyl mustards and the superior activities of cinnamoyl derivatives are the most relevant features of the series.
Journal of the Chemical Society, Perkin Transactions 1, 1993
... Anna Arnoldi," Angela Bassoli, Lucio Merlini and Enzio Ragg Dipartimento di Scienze Mole... more ... Anna Arnoldi," Angela Bassoli, Lucio Merlini and Enzio Ragg Dipartimento di Scienze Molecolari Agroaiimentari, Sezione di Chimica, Universita di Milano, via Celoria 2 ... Lindley and Shallenberger ' attempted to explain the effect in the case of 5-thio-PD-glucose and 6-thio-P ...
Brostallicin (PNU-166196) is a synthetic -bromoacrylic, second- generation DNA minor groove binde... more Brostallicin (PNU-166196) is a synthetic -bromoacrylic, second- generation DNA minor groove binder structurally related to distamycin A, presently in Phase II trials in Europe and the United States. The compound shows broad antitumor activity in preclinical models and dramatically reduced in vitro myelotoxicity in human hematopoietic pro- genitor cells compared with that of other minor groove binders. Brostal- licin showed
Physiologia Plantarum, 1995
... 1995 Capynglu © Flr^,loi;ia Flanlar^,,, IW5 f&amp;#x27;nnU&amp;#x27;iI in ih&... more ... 1995 Capynglu © Flr^,loi;ia Flanlar^,,, IW5 f&amp;#x27;nnU&amp;#x27;iI in ih&amp;#x27;tiinarL - ii!ln^fi!\ reservi-d Germination and pH of intracellular compartments in seeds of PhaceUa tanacetifolia Luca Espen, Silvia Morgutti, Chiara Alisi, Livia Pirovano, Enzio Ragg and Sergio M. Cocucci Espen. ...
Journal of Molecular Biology, 2000
Prion diseases are characterized by the accumulation of altered forms of the prion protein (terme... more Prion diseases are characterized by the accumulation of altered forms of the prion protein (termed PrP Sc ) in the brain. Unlike the normal protein, PrP Sc isoforms have a high content of b-sheet secondary structure, are protease-resistant, and form insoluble aggregates and amyloid ®brils. Evidence indicates that they are responsible for neuropathological changes (i.e. nerve cell degeneration and glial cell activation) and transmissibility of the disease process. Here, we show that the antibiotic tetracycline: (i) binds to amyloid ®brils generated by synthetic peptides corresponding to residues 106-126 and 82-146 of human PrP; (ii) hinders assembly of these peptides into amyloid ®brils; (iii) reverts the protease resistance of PrP peptide aggregates and PrP Sc extracted from brain tissue of patients with Creutzfeldt-Jakob disease; (iv) prevents neuronal death and astrocyte proliferation induced by PrP peptides in vitro. NMR spectroscopy revealed several through-space interactions between aromatic protons of tetracycline and side-chain protons of Ala 117-119 , Val 121-122 and Leu 125 of PrP 106-126. These properties make tetracycline a prototype of compounds with the potential of inactivating the pathogenic forms of PrP.
Bioorganic & Medicinal Chemistry Letters, 2000
AbstractÐThe design, synthesis, and cytotoxic activity of novel benzoyl and cinnamoyl sulfur must... more AbstractÐThe design, synthesis, and cytotoxic activity of novel benzoyl and cinnamoyl sulfur mustard derivatives of distamycin A are described and structure±activity relationships are discussed. These sulfur mustards are more potent cytotoxics than corresponding nitrogen mustards in spite of the lower alkylating power, while their sulfoxide analogues are substantially inactive. Cinnamoyl sulfur mustard derivative proved to be one of the most active distamycin-derived cytotoxics, about 1000 times more potent than melphalan. #
European Journal of Biochemistry, 1994
The aggregative properties of GalNAc-G,,, ganglioside, in comparison with those of G,,,, have bee... more The aggregative properties of GalNAc-G,,, ganglioside, in comparison with those of G,,,, have been investigated and correlated to the intrinsic conformation and mobility of the oligosaccharide chain of the molecules. Micellar parameters in aqueous solution (molecular mass, hydrodynamic radius as well as the surface area at the lipidwater interface and the packing parameter of the monomer inserted in the aggregate) are measured by the laser light-scattering technique. The presence of a further GalNAc residue causes a 22% increase in molecular mass, contrary to expectation. Oligosaccharide moiety three-dimensional structures have been modeled using molecular mechanics and dynamics calculations, based on NOE interactions observed for native gangliosides dissolved in deuterated dimethylsulfoxide or, as mixed micelles with fully deuterated dodecylphosphocholine, in D,O. Compared with G,,, the GalNAc-G,,, is less mobile, thus influencing the surface area, this lower mobility together with the GalNAc-G,,, conformation leads to a larger number of monomers participating in the formation of the micelle. The results further substantiate the model in which the three-dimensional structure and the intrinsic dynamic properties of the oligosaccharide chain affect the geometrical properties of the aggregate. Gangliosides, glycosphingolipids characterized by the presence of sialic acid residue(s) (Wiegandt, 1985), are components of vertebrate cell plasma membrane where they play an important role in a variety of surface events such as recog-Correspondence to S. Sonnino, Dipartimento di Chimica e Fax: +39 2 2363584. Abbreviations. Ganglioside nomenclature is in accordance with Svennerholm (1 980) and the IUPAC-IUB recommendations (1 977, 1982). G,,, 13NeuSAcGalCer, a-NeuSAc-(2-3)-P-Gal-(l-l)-Cer; G,,, I13Neu5AcLacCer, a-NeuSAc-(2-3)-P-Gal-(1-4)-~-Glc-(l-l)-Cer; G,,, I13Neu5AcGgOse,Cer, P-GalNAc-(1-4)-[a-Neu5Ac-(2-3)]-~-Gal-(1-4)-j-Glc-(l-l)-Cer ; G,,, I13NeuSAcGgOse,Cer, P-Gal-(1 -3)-P-GalNAc-( 1-4)-[a-NeuSAc-(2-3)] +Gal-( 1-4)-j?-Glc-(I-l)-Cer; G,,,,, I13Neu5AcGgOse,, P-Ga1-(1-3)-j-GalNAc-(1-4)-[a-NeuSAc-( 2-3)]-b-Gal-( 1 -4)-Glc ; G,,,, IV3NeuSAcI13Neu5AcGg-Ose,Cer, cr-NeuSAc-(2-3)-,8-Gal-( 1 -3)-/7-GalNAc-( 1 -4)-[a-NeuSAc-(2-3)]-P-Gal-( 1 -4)-P-Glc-( 1-1)-Cer ; G,,,,,, IV3NeuSAcI13NeuS-AcGgOse,, a-NeuSAc-(2-3)-P-Gal-(1-3)-P-CalNAc-(1-4)-[a-Neu5-Ac-(2-3)]-P-Gal-(1-4)-Glc ; GalNAc-G,,,, IV4GalNAcIV3-Neu5-AcI13Neu5AcGgOse,Cer, P-GalNAc-(1-4)-[a-NeuSAc-(2-3)]-P-Gal-(
Phytochemistry, 1995
A new derivative of pantoic acid, R( - ) pantoyllactone-β-d glucopyranoside, has been isolated fr... more A new derivative of pantoic acid, R( - ) pantoyllactone-β-d glucopyranoside, has been isolated from rice seedlings and its structure determined. β-Glucosidase hydrolysed it to d-glucose and R( - )pantoyllactone. Alkaline hydrolysis converted it to the salt of 2-R( - )pantoic acid β-d-glucopyranoside. It accumulated in rice shoots but not in roots.
Journal of the Chemical Society, Perkin Transactions 2, 1997
... Stefania Mazzini,a Lucio Merlini,a Rosanna Mondelli,*,a Gianluca Nasini,b Enzio Ragga andLeon... more ... Stefania Mazzini,a Lucio Merlini,a Rosanna Mondelli,*,a Gianluca Nasini,b Enzio Ragga andLeonardo Scaglionia a Dipartimento di Scienze Molecolari Agrolimentari, Sezione di Chimica, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy b Centro del CNR per ...
Steroids, 2006
An improved procedure for the microbial hydroxylations of dehydroepiandrosterone (DHEA, 1) and 15... more An improved procedure for the microbial hydroxylations of dehydroepiandrosterone (DHEA, 1) and 15β,16β-methylene-dehydroepiandrosterone (2) was studied using whole cells of Botryodiplodia malorum and Colletotrichum lini. C. lini catalyzed 7α- and 15α-hydroxylation of 1 and 7α-hydroxylation of 2, while B. malorum gave 7β-hydroxylation of both the substrates. The stability of the enzymatic activity was higher in the presence of co-substrates (i.e.,
European Journal of Biochemistry, 1999
Experimental two-dimensional 1 H NMR data have been obtained for PrP106±128 under the following s... more Experimental two-dimensional 1 H NMR data have been obtained for PrP106±128 under the following solvent conditions: deionized water/2,2,2-trifluoroethanol 50 : 50 (v/v) and dimethylsulfoxide. These data were analyzed by restrained molecular mechanics calculations to determine how changes in solvation affect the conformation of the peptide. In deionized water at pH 3.5, the peptide adopted a helical conformation in the hydrophobic region spanning residues Met112±Leu125, with the most populated helical region corresponding to the Ala115±Ala119 segment (< 10%). In trifluoroethanol/H 2 O, the a-helix increased in population especially in the Gly119±Val122 tract (< 25%). The conformation of this region was found to be remarkably sensitive to pH, as the Ala120±Gly124 tract shifted to an extended conformation at pH 7. In dimethylsulfoxide, the hydrophobic cluster adopted a prevalently extended conformation. For all tested solvents the region spanning residues Asn108±Met112 was present in a`turn-like' conformation and included His111, situated just before the starting point of the a-helix. Rather than by conformational changes, the effect of His111 is exerted by changes in its hydrophobicity, triggering aggregation. The amphiphilic properties and the pH-dependent ionizable side-chain of His111 may thus be important for the modulation of the conformational mobility and heterogeneity of PrP106±126.
Journal of the Chemical Society, Perkin Transactions 2, 1993
ABSTRACT The keto–enol tautomerism of the dihydroxyperylenequinone system of a number of natural ... more ABSTRACT The keto–enol tautomerism of the dihydroxyperylenequinone system of a number of natural compounds, cercosporin 1, isocercosporin 2, phleichrome 3, isophleichrome 4, elsinochromes 5–9, cladochrome C 10, and hypocrellin 11 was studied by 1H, 2H and 13C NMR spectroscopy. 4,9-Dihydroxyperylene-3,10-dione and 3,10-dihydroxyperylene-4,9-dione tautomers were recognized as present in fast equilibrium in CDCl3 and [2H6]acetone solutions. The populations of each tautomer were obtained from the coupling between the proton of the hydrogen-bonded OH groups and the adjacent carbon atoms, i.e. J(C3, OH) and J(C4, OH). The most important factors governing the tautomeric equilibrium in these helix-shaped compounds appeared to be the substituent effects, the strength of the intramolecular phenol–quinone hydrogen bond, the distortion from the planarity of the perylenequinone system, solvation and aggregation effects. The strength of the hydrogen bonds, which is related to the distortion from planarity, was evaluated from 1H chemical shifts and primary deuterium isotope effects. Proton shifts of OH groups and isotope effects are linearly correlated. The influence of solvents and concentration on the tautomeric equilibrium was studied in the case of 4, for which a model of vertical stacking-type dimerisation is proposed.
Acta Chemica Scandinavica, 1986
The 1H NMR spectra of carp parvalbumin saturated with Ca2+, Cd2+, La3+ and Lu3+ were compared, us... more The 1H NMR spectra of carp parvalbumin saturated with Ca2+, Cd2+, La3+ and Lu3+ were compared, using 2D 1H NMR techniques as well as conventional 1H NMR spectra. The Ca2+ and Cd2+ saturated parvalbumin (with both high affinity Ca2+-binding sites occupied) gave rise to very similar spectra. This shows that these two species have almost identical protein conformations. The 1H NMR spectrum from the Ln3+ saturated parvalbumins deviated from the other two and it was therefore concluded that Cd2+ is a better probe for Ca2+ than Ln3+ in parvalbumin and probably also for related calcium binding proteins. The addition of excess of divalent metal ions, such as Mg2+ or Ca2+, causes small changes in the chemical shift of some methyl resonances. This is presumably caused by binding of these metal ions to a third site close to the CD site which is made up of the carboxylic groups from Glu 60 and Asp 61.
Environmental Biosafety Research, 2008
The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil b... more The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil bacterial community structure, and their potential to support horizontal gene transfer (HGT) to bacteria have been studied. Soil microcosms were exposed to root-released compounds collected from transplastomic and non-transgenic tobacco cultivars. Cluster analysis of automated ribosomal intergenic spacer analysis (ARISA) profiles of the soil bacterial community after 48 h incubation grouped the transgenic cultivar apart from the non-transgenic, indicating that it had a rhizodeposition pattern different from the parental plants. However, these differences were less than between the two non-transgenic tobacco cultivars studied. NMR characterization of the rootreleased compounds showed some differences in chemical fingerprinting pattern between the transplastomic and the parental cultivar. However, the effect on bacterial community structure was transient, and tended to disappear after 96 h of incubation. The potential of root-released compounds as a source of transforming DNA for bacteria was investigated by using four potential recipient species. No transformants were obtained following exposure of all the recipients to the root-released compounds. Root-released compounds amended to transgene donor DNA decreased the transformation frequency of Acinetobacter baylyi strain ADP1200, while Azospirillum, Agrobacterium, and Sinorhizobium strains failed to develop competence also in the presence of an external added transgene source. Detection of plastid sequences by PCR suggested that a very low amount of fragmented plastid donor DNA was present in the root-released compounds.
FEBS Journal, 2006
Bowman-Birk serine protease inhibitors are a family of small plant proteins, whose physiological ... more Bowman-Birk serine protease inhibitors are a family of small plant proteins, whose physiological role has not been ascertained as yet, while chemopreventive anticarcinogenic properties have repeatedly been claimed. In this work we present data on the isolation of a lentil (Lens culinaris, L., var. Macrosperma) seed trypsin inhibitor (LCTI) and its functional and structural characterization. LCTI is a 7448 Da double-headed trypsin/chymotrypsin inhibitor with dissociation constants equal to 0.54 nM and 7.25 nM for the two proteases, respectively. The inhibitor is, however, hydrolysed by trypsin in a few minutes timescale, leading to a dramatic loss of its affinity for the enzyme. This is due to a substantial difference in the kon and k*on values (1.1 microM-1.s-1 vs. 0.002 microM-1.s-1), respectively, for the intact and modified inhibitor. A similar behaviour was not observed with chymotrypsin. The twenty best NMR structures concurrently showed a canonical Bowman-Birk inhibitor (BBI) conformation with two antipodal beta-hairpins containing the inhibitory domains. The tertiary structure is stabilized by ion pairs and hydrogen bonds involving the side chain and backbone of Asp10-Asp26-Arg28 and Asp36-Asp52 residues. At physiological pH, the final structure results in an asymmetric distribution of opposite charges with a negative electrostatic potential, centred on the C-terminus, and a highly positive potential, surrounding the antitryptic domain. The segment 53-55 lacks the anchoring capacity found in analogous BBIs, thus rendering the protein susceptible to hydrolysis. The inhibitory properties of LCTI, related to the simultaneous presence of two key amino acids (Gln18 and His54), render the molecule unusual within the natural Bowman-Birk inhibitor family.
European Journal of Biochemistry, 1996
The non-denaturing substitution of cluster iron by other metals was studied in spinach ferredoxin... more The non-denaturing substitution of cluster iron by other metals was studied in spinach ferredoxin and in bovine adrenodoxin. Only some of several metal species tested (Cd", Znz+, VO", Mnz+, Co2+, Ni") caused bleaching of the residual visible absorbance and of the EPR signals of the reduced ferredoxins. No formation of mixed-metal cluster was observed. The most reactive metal species were Cd2+ and Zn2+, and CdZi was found to react also with oxidized adrenodoxin. Metal-treated proteins were resolved into a mixture of apoprotein, metal-substituted protein and unreacted holoprotein. Their biological activity was proportional to the residual holoprotein concentration. Spinach ferredoxin and adrenodoxin were found to differ substantially with regard to their metal-substitution reactivity under oxidizing and reducing conditions, reaction time, and formation of apoprotein, which was more pronounced for spinach ferredoxin. Exchange of cluster iron with Cd" in adrenodoxin generated stable species containing 2 mol sulfide/mol protein, and 2 or 5 mol cadmiudmol protein, respectively. The relative amount of the two substitution products depended on the experimental conditions. CD and NMR data on all the cadmiumsubstituted proteins suggest that iron replacement led to a significant structural rearrangement. Nevertheless, all the metal-substituted proteins could be re-converted into the native iron-containing form upon incubation with iron in the absence of reductants, of denaturing agents, and of an external source of sulfide. The different reactivity of the two proteins is discussed in terms of the cluster environment, along with the possible physiological relevance of these findings.
Tetrahedron, 2000
Novel hybrid porphyrins bearing two and four suitably protected glycosidic units appended at the ... more Novel hybrid porphyrins bearing two and four suitably protected glycosidic units appended at the meso positions of the central macrocycle through robust carboncarbon bonds have been constructed and characterized. Metallation of these constructs with certain bivalent metal ...
PLOS One, 2010
An understanding of the integrated relationships among the principal cellular functions that gove... more An understanding of the integrated relationships among the principal cellular functions that govern the bioenergetic reactions of an organism is necessary to determine how cells remain viable and optimise their fitness in the environment. Urease is a complex enzyme that catalyzes the hydrolysis of urea to ammonia and carbonic acid. While the induction of urease activity by several microorganisms has
Physiologia Plantarum, 1992
Menegus, F, Cattarazza, L., Scaglioni, L. and Ragg, E. 1992. Effects of oxygen level on metabolis... more Menegus, F, Cattarazza, L., Scaglioni, L. and Ragg, E. 1992. Effects of oxygen level on metabolism and development of seedlings of Trapa natans and two ecologically related spedes. -Physioi. Plant. 86; 168-172.
The Journal of Organic Chemistry, 1995
... Sergio Riva and Anna Bertinotti CNR, Istituto di Chimica degli Ormoni, Via Mario Bianco 9, 2... more ... Sergio Riva and Anna Bertinotti CNR, Istituto di Chimica degli Ormoni, Via Mario Bianco 9, 20131 Milano, Italy Enzio Ragg and Leonard0 Scaglioni ... (4) (a) Danieli, B.; De Bellis, P.; Carrea, G.; Riva, S. Heterocycles 1989,29, 2061. ...