Josefa Donoso | Universitat de les Illes Balears (original) (raw)

Papers by Josefa Donoso

Research paper thumbnail of Band-shape analysis and resolution of electronic spectra of pyridoxal 5′-phosphate with amino acids

Journal of the Chemical Society, 1991

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Research paper thumbnail of Cyclic nucleotide binding to cAMP receptor protein from Escherichia coli. Optical and ligand-binding studies

European journal of biochemistry, Nov 1, 1987

cAMP receptor protein from Escherichia coli has been purified on a large scale. Analogues of cAMP... more cAMP receptor protein from Escherichia coli has been purified on a large scale. Analogues of cAMP modified on the 6‐NH2 group of the adenosine ring, the ribose 2′OH group or the cyclic phosphate are able to displace cAMP from its binding site with dissociation constants of similar magnitude to that of cAMP. More extensive modification produces weaker binding. Ultraviolet/visible difference spectroscopy and fluorescence spectroscopy show that the environment of the bound adenosine moiety is considerably less polar than that in aqueous solvent, while an anthraniloyl group substituted on the 2′OH position remains accessible to solvent. The 2‐NH2 group of cGMP appears to be protonated in the bound form, while no change in the charge state of cAMP is apparent.

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Research paper thumbnail of Quantitative description oftheabsorption spectra ofthecoenzyme in glycogen phosphorylases based onlog-normal distribution curves

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Research paper thumbnail of Amino acid catalytic effect on the transamination reaction between pyridoxal 5′-phosphate and L-serine

Journal of molecular catalysis, Aug 1, 1991

Abstract The kinetic study of Schiff base formation between pyridoxal 5′-phosphate (PLP) and L-se... more Abstract The kinetic study of Schiff base formation between pyridoxal 5′-phosphate (PLP) and L-serine and its subsequent transamination to yield pyridoxamine 5′-phosphate (PMP) and ketoacidate ion has been carried out over a wide pH range by fluorescence and UV—Vis measurements. The kinetic constants of Schiff base formation are compared with constants of other PLP—amino acid systems, showing the existence of an intramolecular general acid catalysis of PLP and general basic catalysis of the amino acid. The rate-determining step of the schiff base transamination is the isomerization of this compound to ketoimine, since the rate constants for disappearance of Schiff base coincide with the rate constants for PMP formation. This process is catalyzed by the OH−/H2O system and the monoprotonated amino acid.

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Research paper thumbnail of Influence of the side chain on the stability of Schiff-bases formed between pyridoxal 5′-phosphate and amino acids

International Journal of Chemical Kinetics, Sep 1, 1990

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Research paper thumbnail of ChemInform Abstract: Influence of the Side Chain on the Stability of Schiff-Bases Formed Between Pyridoxal 5′-Phosphate and Amino Acids

ChemInform, Nov 27, 1990

From the kinetic study of the pH‐dependence of the hydrolysis of (I) or the analogue of the ε‐ami... more From the kinetic study of the pH‐dependence of the hydrolysis of (I) or the analogue of the ε‐aminocaproic acid, it is shown that the absence of ionic groups in the surroundings of the C=N bond must be an important factor of stability.

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Research paper thumbnail of ChemInform Abstract: The Degradation Mechanism of an Oral Cephalosporin: Cefaclor

ChemInform, Aug 4, 2010

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Research paper thumbnail of A method, based on statistical moments, to evaluate the kinetic parameters involved in unstable enzyme systems

Journal of Mathematical Chemistry, 2007

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Research paper thumbnail of DFT Studies on Schiff Base Formation of Vitamin B6 Analogues. Reaction between a Pyridoxamine-Analogue and Carbonyl Compounds

Journal of Physical Chemistry A, Mar 17, 2010

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Research paper thumbnail of Theoretical pKa calculations of aminoacids and peptides

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Research paper thumbnail of A comparative study of non-enzymatic glycation of Lysozyme by two glycating agents: methylglyoxal and glycolaldehyde

Journal of the International Society of Antioxidants in Nutrition & Health, May 30, 2016

Non-enzymatic glycation of proteins is a post-translational modification process which plays an i... more Non-enzymatic glycation of proteins is a post-translational modification process which plays an important role in diabetes mellitus [1]. It involves covalent bond formation between free amino groups of proteins and reducing sugars that affects the physical and functional properties of proteins [2]. The present study was aimed at the investigation of the effects of glycation of hen egg white lysozyme (HEWL) by methylglyoxal and glycolaldehyde. The objectives of this study were to evaluate the enzyme activity during the glycation process, to identify the structures of advanced glycation end products (AGEs) formed on glycated HEWL, to investigate the effect of glycation on the secondary structure of glycated HEWL, and to analyse the morphology of the resulting aggregates. By using interdisciplinary techniques, we have shown that the kinetic rate of enzymatic activity loss of HEWL by methylglyoxal is two times higher than that for glycolaldehyde. Nevertheless, no changes in the secondary structure of HEWL were detected by CD. Furthermore, AGEs formed in the glycated HEWL by methylglyoxal promotes cross-linking in the glycated enzyme. Finally, the resulting aggregates exhibit the same spherical morphology but with different size (glycolaldehyde induces formation of bigger aggregates).

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Research paper thumbnail of On the molecular mechanism that links glycation with aggregation: the case of lysozyme glycated with ribose

Journal of the International Society of Antioxidants in Nutrition & Health, May 30, 2016

Protein glycation (PG) usually induces the loss of protein function and consequently, the develop... more Protein glycation (PG) usually induces the loss of protein function and consequently, the development of diabetes-related diseases1. It has been assumed that this process occurs as a result of a structural modification induced by PG, which is also able to trigger protein aggregation. Therefore, neurodegenerative disorders such as Parkinson or Alzheimer diseases increase their prevalence under diabetes mellitus. Trying to describe in detail the molecular mechanism that links PG with protein aggregation we have studied the glycation of lysozyme (HEWL) with ribose2. HEWL has been used as a model since it holds a reduced aggregation tendency under its native state and possesses putative glycation targets (lysine and arginine)3. On the other hand, ribose induces protein aggregation4 and it physiological concentration rapidly rises in diabetic patients5. Through the combination of different biophysical techniques (NMR, CD, SAXS, etc.), we have proved that HEWL glycation mediated by ribose mainly occurs on lysine without altering the protein structure. However, glycation induces a change on the overall protein charge generating different hydrophobic patches which are responsible for the native aggregation of glycated HEWL. This aggregation process initiates with the formation of soluble oligomers which finally assemble to form insoluble aggregates.

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Research paper thumbnail of La química, protagonista en las Islas Baleares durante el año 2011

Anales de Química, Jul 1, 2012

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Research paper thumbnail of Theoretical Calculations of β-Lactam Antibiotics. Part VI. AM1 calculations of alkaline hydrolysis of clavulanic acid

Helvetica Chimica Acta, Sep 21, 1994

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Research paper thumbnail of Theoretical Calculations of β-Lactam Antibiotics. Part VII. Influence of the solvent on the basic hydrolysis of the β-lactam ring

Helvetica Chimica Acta, Mar 20, 1996

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Research paper thumbnail of Theoretical calculations of β-lactam antibiotics. III. AM1, MNDO, and MINDO/3 calculations of hydrolysis of β-lactam compound (azetidin-2-one ring)

Journal of Computational Chemistry, Jul 1, 1992

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Research paper thumbnail of ChemInform Abstract: Theoretical Calculations of β-Lactam Antibiotics. Part 6. AM1 Calculations of Alkaline Hydrolysis of Clavulanic Acid (I)

ChemInform, Aug 18, 2010

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Research paper thumbnail of Transimination reaction between pyridoxal-<i>5′</i>-phosphate schiff bases with dodecylamine and amino acids

Journal of Physical Organic Chemistry, Mar 1, 1992

Some transimination processes were studied using an intermolecular model formed by pyridoxal‐5′ ‐... more Some transimination processes were studied using an intermolecular model formed by pyridoxal‐5′ ‐phosphate (PLP) an amino acid and dodecylamine (DOD) in an aqueous medium. All the kinetic constants for the reversible reaction were determined. The results show that in these cases transimination proceeds through an addition‐elimination by forming a diamine geminal intermediate. Equilibria are always shifted to dodecylamine‐PLP Schiff base formation. Differences between the stability of this Schiff base and the ϵ‐aminocaproic Schiff base cannot be explained only on the basis of the different nucleophicities of amine groups and therefore differences in the imine double bond environment must be taken into account to explain this behaviour.

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Research paper thumbnail of Theoretical calculations of ?-lactam antibiotics

Theoretica chimica acta, Aug 1, 1993

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Research paper thumbnail of Using B-Learning in Chemistry and Biochemistry Degrees

EDULEARN10 Proceedings, 2010

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Research paper thumbnail of Band-shape analysis and resolution of electronic spectra of pyridoxal 5′-phosphate with amino acids

Journal of the Chemical Society, 1991

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Research paper thumbnail of Cyclic nucleotide binding to cAMP receptor protein from Escherichia coli. Optical and ligand-binding studies

European journal of biochemistry, Nov 1, 1987

cAMP receptor protein from Escherichia coli has been purified on a large scale. Analogues of cAMP... more cAMP receptor protein from Escherichia coli has been purified on a large scale. Analogues of cAMP modified on the 6‐NH2 group of the adenosine ring, the ribose 2′OH group or the cyclic phosphate are able to displace cAMP from its binding site with dissociation constants of similar magnitude to that of cAMP. More extensive modification produces weaker binding. Ultraviolet/visible difference spectroscopy and fluorescence spectroscopy show that the environment of the bound adenosine moiety is considerably less polar than that in aqueous solvent, while an anthraniloyl group substituted on the 2′OH position remains accessible to solvent. The 2‐NH2 group of cGMP appears to be protonated in the bound form, while no change in the charge state of cAMP is apparent.

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Research paper thumbnail of Quantitative description oftheabsorption spectra ofthecoenzyme in glycogen phosphorylases based onlog-normal distribution curves

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Research paper thumbnail of Amino acid catalytic effect on the transamination reaction between pyridoxal 5′-phosphate and L-serine

Journal of molecular catalysis, Aug 1, 1991

Abstract The kinetic study of Schiff base formation between pyridoxal 5′-phosphate (PLP) and L-se... more Abstract The kinetic study of Schiff base formation between pyridoxal 5′-phosphate (PLP) and L-serine and its subsequent transamination to yield pyridoxamine 5′-phosphate (PMP) and ketoacidate ion has been carried out over a wide pH range by fluorescence and UV—Vis measurements. The kinetic constants of Schiff base formation are compared with constants of other PLP—amino acid systems, showing the existence of an intramolecular general acid catalysis of PLP and general basic catalysis of the amino acid. The rate-determining step of the schiff base transamination is the isomerization of this compound to ketoimine, since the rate constants for disappearance of Schiff base coincide with the rate constants for PMP formation. This process is catalyzed by the OH−/H2O system and the monoprotonated amino acid.

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Research paper thumbnail of Influence of the side chain on the stability of Schiff-bases formed between pyridoxal 5′-phosphate and amino acids

International Journal of Chemical Kinetics, Sep 1, 1990

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Research paper thumbnail of ChemInform Abstract: Influence of the Side Chain on the Stability of Schiff-Bases Formed Between Pyridoxal 5′-Phosphate and Amino Acids

ChemInform, Nov 27, 1990

From the kinetic study of the pH‐dependence of the hydrolysis of (I) or the analogue of the ε‐ami... more From the kinetic study of the pH‐dependence of the hydrolysis of (I) or the analogue of the ε‐aminocaproic acid, it is shown that the absence of ionic groups in the surroundings of the C=N bond must be an important factor of stability.

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Research paper thumbnail of ChemInform Abstract: The Degradation Mechanism of an Oral Cephalosporin: Cefaclor

ChemInform, Aug 4, 2010

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Research paper thumbnail of A method, based on statistical moments, to evaluate the kinetic parameters involved in unstable enzyme systems

Journal of Mathematical Chemistry, 2007

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Research paper thumbnail of DFT Studies on Schiff Base Formation of Vitamin B6 Analogues. Reaction between a Pyridoxamine-Analogue and Carbonyl Compounds

Journal of Physical Chemistry A, Mar 17, 2010

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Research paper thumbnail of Theoretical pKa calculations of aminoacids and peptides

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A comparative study of non-enzymatic glycation of Lysozyme by two glycating agents: methylglyoxal and glycolaldehyde

Journal of the International Society of Antioxidants in Nutrition & Health, May 30, 2016

Non-enzymatic glycation of proteins is a post-translational modification process which plays an i... more Non-enzymatic glycation of proteins is a post-translational modification process which plays an important role in diabetes mellitus [1]. It involves covalent bond formation between free amino groups of proteins and reducing sugars that affects the physical and functional properties of proteins [2]. The present study was aimed at the investigation of the effects of glycation of hen egg white lysozyme (HEWL) by methylglyoxal and glycolaldehyde. The objectives of this study were to evaluate the enzyme activity during the glycation process, to identify the structures of advanced glycation end products (AGEs) formed on glycated HEWL, to investigate the effect of glycation on the secondary structure of glycated HEWL, and to analyse the morphology of the resulting aggregates. By using interdisciplinary techniques, we have shown that the kinetic rate of enzymatic activity loss of HEWL by methylglyoxal is two times higher than that for glycolaldehyde. Nevertheless, no changes in the secondary structure of HEWL were detected by CD. Furthermore, AGEs formed in the glycated HEWL by methylglyoxal promotes cross-linking in the glycated enzyme. Finally, the resulting aggregates exhibit the same spherical morphology but with different size (glycolaldehyde induces formation of bigger aggregates).

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Research paper thumbnail of On the molecular mechanism that links glycation with aggregation: the case of lysozyme glycated with ribose

Journal of the International Society of Antioxidants in Nutrition & Health, May 30, 2016

Protein glycation (PG) usually induces the loss of protein function and consequently, the develop... more Protein glycation (PG) usually induces the loss of protein function and consequently, the development of diabetes-related diseases1. It has been assumed that this process occurs as a result of a structural modification induced by PG, which is also able to trigger protein aggregation. Therefore, neurodegenerative disorders such as Parkinson or Alzheimer diseases increase their prevalence under diabetes mellitus. Trying to describe in detail the molecular mechanism that links PG with protein aggregation we have studied the glycation of lysozyme (HEWL) with ribose2. HEWL has been used as a model since it holds a reduced aggregation tendency under its native state and possesses putative glycation targets (lysine and arginine)3. On the other hand, ribose induces protein aggregation4 and it physiological concentration rapidly rises in diabetic patients5. Through the combination of different biophysical techniques (NMR, CD, SAXS, etc.), we have proved that HEWL glycation mediated by ribose mainly occurs on lysine without altering the protein structure. However, glycation induces a change on the overall protein charge generating different hydrophobic patches which are responsible for the native aggregation of glycated HEWL. This aggregation process initiates with the formation of soluble oligomers which finally assemble to form insoluble aggregates.

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Research paper thumbnail of La química, protagonista en las Islas Baleares durante el año 2011

Anales de Química, Jul 1, 2012

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Research paper thumbnail of Theoretical Calculations of β-Lactam Antibiotics. Part VI. AM1 calculations of alkaline hydrolysis of clavulanic acid

Helvetica Chimica Acta, Sep 21, 1994

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Research paper thumbnail of Theoretical Calculations of β-Lactam Antibiotics. Part VII. Influence of the solvent on the basic hydrolysis of the β-lactam ring

Helvetica Chimica Acta, Mar 20, 1996

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Research paper thumbnail of Theoretical calculations of β-lactam antibiotics. III. AM1, MNDO, and MINDO/3 calculations of hydrolysis of β-lactam compound (azetidin-2-one ring)

Journal of Computational Chemistry, Jul 1, 1992

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Research paper thumbnail of ChemInform Abstract: Theoretical Calculations of β-Lactam Antibiotics. Part 6. AM1 Calculations of Alkaline Hydrolysis of Clavulanic Acid (I)

ChemInform, Aug 18, 2010

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Research paper thumbnail of Transimination reaction between pyridoxal-<i>5′</i>-phosphate schiff bases with dodecylamine and amino acids

Journal of Physical Organic Chemistry, Mar 1, 1992

Some transimination processes were studied using an intermolecular model formed by pyridoxal‐5′ ‐... more Some transimination processes were studied using an intermolecular model formed by pyridoxal‐5′ ‐phosphate (PLP) an amino acid and dodecylamine (DOD) in an aqueous medium. All the kinetic constants for the reversible reaction were determined. The results show that in these cases transimination proceeds through an addition‐elimination by forming a diamine geminal intermediate. Equilibria are always shifted to dodecylamine‐PLP Schiff base formation. Differences between the stability of this Schiff base and the ϵ‐aminocaproic Schiff base cannot be explained only on the basis of the different nucleophicities of amine groups and therefore differences in the imine double bond environment must be taken into account to explain this behaviour.

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Research paper thumbnail of Theoretical calculations of ?-lactam antibiotics

Theoretica chimica acta, Aug 1, 1993

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Using B-Learning in Chemistry and Biochemistry Degrees

EDULEARN10 Proceedings, 2010

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