Mariella Dentini | Università degli Studi "La Sapienza" di Roma (original) (raw)
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Papers by Mariella Dentini
Aqueous Solution Properties of Bacterial Poly-γ- D -glutamate
ACS Symposium Series, 1996
Polyelectrolytic Behavior of Ionic Polysaccharides
ACS Symposium Series, 1981
Microbes in Polymer Chemistry
ACS Symposium Series, 1996
ABSTRACT
New hydrogels based on carbohydrate and on carbohydrate-synthetic polymer networks
Polymer Gels and Networks, 1997
Novel synthetic routes recently explored in our laboratories in order to obtain crosslinked polym... more Novel synthetic routes recently explored in our laboratories in order to obtain crosslinked polymeric samples, comprising either chitosan or gellan as polysaccharidic components, are outlined. The former networks, in which different crosslinking partners have been used (i.e. oxidized cyclodextrin and telechelic poly(vinylalcohol)), can bear fixed positive charges while the latter are anionic. Zwitterionic networks formed by the template polymerization of
Fig.1 a-b) Scaffolds morphology as revealed by Scanning Electron Miscroscopy. c-d) Local porosity... more Fig.1 a-b) Scaffolds morphology as revealed by Scanning Electron Miscroscopy. c-d) Local porosity distribution, μ(φ), and local percolation probability, λ(φ), as a function of the porosity, φ, for the two different systems investigated by means of DS. a) b) c) d)
Guar gum, a -D-(1f4)-linked D-mannan with R-D-galactopyranosyl units attached as side groups, was... more Guar gum, a -D-(1f4)-linked D-mannan with R-D-galactopyranosyl units attached as side groups, was treated with R-galactosidase, an enzyme that splits off the R-D-galactosyl units to obtain a galactomannan with a low galactose content. The galactose-depleted polysaccharide was then selectively oxidized in C(6) position and epimerized using mannuronan C(5)-epimerases, namely AlgE1, AlgE4, AlgE6, and their mixtures, obtaining new pseudo-alginates. In this paper, we report a full high field 1D and 2D NMR study of guar gum as such and of the galactose-depleted, oxidized and epimerized compounds, respectively. From the 1 H NMR spectra, the degree of epimerization, the distribution of mannuronic acid (M) and guluronic acid (G) residues and the average G-block length, N G>1 , were obtained. By means of NMR diffusion experiments, it was also shown that no significant degradation of the polysaccharide occurs as a consequence of the epimerization reactions.
Enzymatic Epimerization of Bacterial Mannuronan and of C-6 Oxidized, Galactose-Depleted Guar: A Circular Dichroism and 1H NMR Study
Attention has been focused on two uronans, namely, mannuronan and galactose-depleted C-6 oxidized... more Attention has been focused on two uronans, namely, mannuronan and galactose-depleted C-6 oxidized guar, the former of microbial origin and the latter of artificial nature, to provide original data on the extent of epimerization they can undergo in dilute aqueous solution using two C-5 mannuronic acid epimerizing enzymes, that is, AlgE-4 and AlgE-6, alone or in admixture. Original circular dichroism data coupled with 1H NMR spectra clearly point out that both uronans can be epimerized, depending on the enzyme or enzyme mixture used, to high levels yielding guluronic-rich alginate samples and guluronic-rich heteropolysaccharides, respectively. Mannuronan and its epimerization products can easily form clear, firm aqueous gels when an excess of HCl is added or when mixed with aqueous CaCl2, respectively. Depleted-guarox does not gel upon addition of excess HCl, while the heterouronan derived from it having a percent of epimerization nearly identical to that of epimerized mannuronan, that is, ca. 70%, can form gel in the presence of Ca(II) only at higher polymer and Ca(II) concentrations. With the latter, heterouronan alpha-D-galacturonic side groups exert hindrance to "junction zone" formation.
Sapienza Università di Roma, Italy Microfluidics is the science of handling fluids at the micrometric scale. The small quantities, low velocities and laminar flows that characterize the movement of liquids and gases inside microfluidic chips, and the confinement in microchannels of opportune geom...
Conformational analysis of DNA-polypeptide systems
STRUCTURE AND OPTICAL-PROPERTIES OF SCHIFF-BASES OF ORTHO-HYDROXYBENZALDEHYDE, META-HYDROXYBENZALDEHYDE AND PARA-HYDROXYBENZALDEHYDE WITH BASIC POLYPEPTIDES
Conformational studies on the pyridoxal Schiff bases of polypeptides
ABSTRACT
CONFORMATION DEPENDENT INTERACTIONS IN IONIC-POLYSACCHARIDE SOLUTIONS
Physical, Inorganic, and Analytical
... Implications for the Synergism of Antimony and Chlorine. William H. Starnes, Jr., Yun M. Kang... more ... Implications for the Synergism of Antimony and Chlorine. William H. Starnes, Jr., Yun M. Kang, and Lynda B. Payne. Chapter 20, pp 253-266. Publication Date (Print): September 15, 2001 (Chapter). DOI: 10.1021/bk-2001-0797.ch020. ...
Calorimetric data on salt induced conformational transition of ionic polysaccharides in aqueous solution
PHYSICOCHEMICAL ASPECTS OF SOME MICROBIAL POLYSACCHARIDES AND THEIR DERIVATIVES
QUASI-ELASTIC LIGHT SCATTERING FROM SENIDILUTE SOLUTIONS OF CELLULOSE-TRI-CARBANILATE AND A MODIFIED XANTHAN
CALORIMETRIC CHARACTERIZATION OF POLYSACCHARIDE POLYELECTROLYTE SOLUTIONS
Two new methods of insolubi1izing in cellulose triacetate membranes, natural or synthetic polyele... more Two new methods of insolubi1izing in cellulose triacetate membranes, natural or synthetic polyelectrolytes, able to bind heavy metal ions, were experimented and discussed. The efficiency of the obtained membranes was tested by monitoring the cupric ion adsorption with a copper ion selective electrode (ISE).
PHYSICOCHEMICAL CHARACTERIZATION OF PARTIAL ESTERS OF POLYURONANS
Hydrogels based on carbohydrate and on polysaccharide-synthetic polymers networks
Aqueous Solution Properties of Bacterial Poly-γ- D -glutamate
ACS Symposium Series, 1996
Polyelectrolytic Behavior of Ionic Polysaccharides
ACS Symposium Series, 1981
Microbes in Polymer Chemistry
ACS Symposium Series, 1996
ABSTRACT
New hydrogels based on carbohydrate and on carbohydrate-synthetic polymer networks
Polymer Gels and Networks, 1997
Novel synthetic routes recently explored in our laboratories in order to obtain crosslinked polym... more Novel synthetic routes recently explored in our laboratories in order to obtain crosslinked polymeric samples, comprising either chitosan or gellan as polysaccharidic components, are outlined. The former networks, in which different crosslinking partners have been used (i.e. oxidized cyclodextrin and telechelic poly(vinylalcohol)), can bear fixed positive charges while the latter are anionic. Zwitterionic networks formed by the template polymerization of
Fig.1 a-b) Scaffolds morphology as revealed by Scanning Electron Miscroscopy. c-d) Local porosity... more Fig.1 a-b) Scaffolds morphology as revealed by Scanning Electron Miscroscopy. c-d) Local porosity distribution, μ(φ), and local percolation probability, λ(φ), as a function of the porosity, φ, for the two different systems investigated by means of DS. a) b) c) d)
Guar gum, a -D-(1f4)-linked D-mannan with R-D-galactopyranosyl units attached as side groups, was... more Guar gum, a -D-(1f4)-linked D-mannan with R-D-galactopyranosyl units attached as side groups, was treated with R-galactosidase, an enzyme that splits off the R-D-galactosyl units to obtain a galactomannan with a low galactose content. The galactose-depleted polysaccharide was then selectively oxidized in C(6) position and epimerized using mannuronan C(5)-epimerases, namely AlgE1, AlgE4, AlgE6, and their mixtures, obtaining new pseudo-alginates. In this paper, we report a full high field 1D and 2D NMR study of guar gum as such and of the galactose-depleted, oxidized and epimerized compounds, respectively. From the 1 H NMR spectra, the degree of epimerization, the distribution of mannuronic acid (M) and guluronic acid (G) residues and the average G-block length, N G>1 , were obtained. By means of NMR diffusion experiments, it was also shown that no significant degradation of the polysaccharide occurs as a consequence of the epimerization reactions.
Enzymatic Epimerization of Bacterial Mannuronan and of C-6 Oxidized, Galactose-Depleted Guar: A Circular Dichroism and 1H NMR Study
Attention has been focused on two uronans, namely, mannuronan and galactose-depleted C-6 oxidized... more Attention has been focused on two uronans, namely, mannuronan and galactose-depleted C-6 oxidized guar, the former of microbial origin and the latter of artificial nature, to provide original data on the extent of epimerization they can undergo in dilute aqueous solution using two C-5 mannuronic acid epimerizing enzymes, that is, AlgE-4 and AlgE-6, alone or in admixture. Original circular dichroism data coupled with 1H NMR spectra clearly point out that both uronans can be epimerized, depending on the enzyme or enzyme mixture used, to high levels yielding guluronic-rich alginate samples and guluronic-rich heteropolysaccharides, respectively. Mannuronan and its epimerization products can easily form clear, firm aqueous gels when an excess of HCl is added or when mixed with aqueous CaCl2, respectively. Depleted-guarox does not gel upon addition of excess HCl, while the heterouronan derived from it having a percent of epimerization nearly identical to that of epimerized mannuronan, that is, ca. 70%, can form gel in the presence of Ca(II) only at higher polymer and Ca(II) concentrations. With the latter, heterouronan alpha-D-galacturonic side groups exert hindrance to "junction zone" formation.
Sapienza Università di Roma, Italy Microfluidics is the science of handling fluids at the micrometric scale. The small quantities, low velocities and laminar flows that characterize the movement of liquids and gases inside microfluidic chips, and the confinement in microchannels of opportune geom...
Conformational analysis of DNA-polypeptide systems
STRUCTURE AND OPTICAL-PROPERTIES OF SCHIFF-BASES OF ORTHO-HYDROXYBENZALDEHYDE, META-HYDROXYBENZALDEHYDE AND PARA-HYDROXYBENZALDEHYDE WITH BASIC POLYPEPTIDES
Conformational studies on the pyridoxal Schiff bases of polypeptides
ABSTRACT
CONFORMATION DEPENDENT INTERACTIONS IN IONIC-POLYSACCHARIDE SOLUTIONS
Physical, Inorganic, and Analytical
... Implications for the Synergism of Antimony and Chlorine. William H. Starnes, Jr., Yun M. Kang... more ... Implications for the Synergism of Antimony and Chlorine. William H. Starnes, Jr., Yun M. Kang, and Lynda B. Payne. Chapter 20, pp 253-266. Publication Date (Print): September 15, 2001 (Chapter). DOI: 10.1021/bk-2001-0797.ch020. ...
Calorimetric data on salt induced conformational transition of ionic polysaccharides in aqueous solution
PHYSICOCHEMICAL ASPECTS OF SOME MICROBIAL POLYSACCHARIDES AND THEIR DERIVATIVES
QUASI-ELASTIC LIGHT SCATTERING FROM SENIDILUTE SOLUTIONS OF CELLULOSE-TRI-CARBANILATE AND A MODIFIED XANTHAN
CALORIMETRIC CHARACTERIZATION OF POLYSACCHARIDE POLYELECTROLYTE SOLUTIONS
Two new methods of insolubi1izing in cellulose triacetate membranes, natural or synthetic polyele... more Two new methods of insolubi1izing in cellulose triacetate membranes, natural or synthetic polyelectrolytes, able to bind heavy metal ions, were experimented and discussed. The efficiency of the obtained membranes was tested by monitoring the cupric ion adsorption with a copper ion selective electrode (ISE).
PHYSICOCHEMICAL CHARACTERIZATION OF PARTIAL ESTERS OF POLYURONANS
Hydrogels based on carbohydrate and on polysaccharide-synthetic polymers networks