Browsing by Author "Ferrer Meli, Irene del Carmen"

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    Isolation and photo-oxidation of lysozyme fragments
    (1981) Ferrer Meli, Irene del Carmen; Silva, E.
    Reduction of the four disulfide bonds and further carboxymethylation of lysozyme followed by its reaction with CNBr brings about L-I, (aa 1 12) and L-II-III (aa 13 129) peptides. When breaking the polypeptidic chain by CNBr action and freeing the peptides formed through S-S bonds reduction and carboxymethylation three peptides are obtained corresponding to L-I (aa 1 12), L-II (aa 13 105) and L-III (aa 106 129). L-II-III, L-III and L-II peptides were separately subjected to photo-oxidation in presence of riboflavin, in 0.05 M phosphate buffer, pH 7.0. The kinetic analysis of Trp photo-oxidation in L-II-III peptides shows that these residues keep, to a great extent, the degree of exposition they had in native lysozyme. L-II peptide also presents Trp residues with a different degree of exposition. Presence of Tyr photo-oxidation in L-II and L-II-III peptides - what does not take place in native lysozyme - suggests a relationship between photo-oxidation selectivity and the degree of exposition of certain amino acid residues in spatial configuration.Reduction of the four disulfide bonds and further carboxymethylation of lysozyme followed by its reaction with CNBr brings about L-I, (aa 1 12) and L-II-III (aa 13 129) peptides. When breaking the polypeptidic chain by CNBr action and freeing the peptides formed through S-S bonds reduction and carboxymethylation three peptides are obtained corresponding to L-I (aa 1 12), L-II (aa 13 105) and L-III (aa 106 129). L-II-III, L-III and L-II peptides were separately subjected to photo-oxidation in presence of riboflavin, in 0.05 M phosphate buffer, pH 7.0. The kinetic analysis of Trp photo-oxidation in L-II-III peptides shows that these residues keep, to a great extent, the degree of exposition they had in native lysozyme. L-II peptide also presents Trp residues with a different degree of exposition. Presence of Tyr photo-oxidation in L-II and L-II-III peptides - what does not take place in native lysozyme - suggests a relationship between photo-oxidation selectivity and the degree of exposition of certain amino acid residues in spatial configuration.Reduction of the four disulfide bonds and further carboxymethylation of lysozyme followed by its reaction with CNBr brings about L-I, (aa 1 12) and L-II-III (aa 13 129) peptides. When breaking the polypeptidic chain by CNBr action and freeing the peptides formed through S-S bonds reduction and carboxymethylation three peptides are obtained corresponding to L-I (aa 1 12), L-II (aa 13 105) and L-III (aa 106 129). L-II-III, L-III and L-II peptides were separately subjected to photo-oxidation in presence of riboflavin, in 0.05 M phosphate buffer, pH 7.0. The kinetic analysis of Trp photo-oxidation in L-II-III peptides shows that these residues keep, to a great extent, the degree of exposition they had in native lysozyme. L-II peptide also presents Trp residues with a different degree of exposition. Presence of Tyr photo-oxidation in L-II and L-II-III peptides - what does not take place in native lysozyme - suggests a relationship between photo-oxidation selectivity and the degree of exposition of certain amino acid residues in spatial configuration.
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    Study of a photo-induced lysozyme-riboflavin bond
    (1985) Ferrer Meli, Irene del Carmen; Silva, E.
    Irradiation of lysozyme in the presence of riboflavin results in the formation of a lysozyme-riboflavin adduct. Reduction and carboxymethylation of the four disulfide bonds as well as the chemical modification of the Tyr residues and the photochemical alteration of the His residue in lysozyme, do not affect the formation of the photo-induced lysozyme-riboflavin bond. When the lysozyme-riboflavin adduct was subjected to mild acid hydrolysis and ion exchange chromatography, the retention of a compound containing14C-riboflavin was observed. Free14C-riboflavin, on the contrary is not retained by the column. The photo-oxidation of free Trp in the presence of14C-riboflavin, gave a compound which bound to the ion exchange resin like the above-mentioned derivative. The photo-oxidation of the Trp residues in lysozyme and in peptides obtained from lysozyme showed very high quantum yields, and these values were directly related to the incorporation of14C-riboflavin in these samples.
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    Thiourea effect on the lignin biodegradation
    (1987) Ferrer Meli, Irene del Carmen; Duran, Nelson
    Lignin degradation by peroxidase or an extracellular crude ligninase in the presence of thiourea is enhanced. Veratryl alcohol, exhibits the same behaviour in both cases. Thiourea is proposed as an additive in biopulping