RESUMEN
Buffalo chymosin was isolated from abomasum mucosa extract of buffalo calves by affinity chromatography on gramicidin S-agarose followed by ion exchange chromatography on gamma-aminopropylsilochrom. Its molecular weight, 36 +/- 1 kDa, is similar to that of bovine calf chymosin. The N-terminal sequence Gly-Glu-Val-Ala-Ser-Val-Pro- coincides with that of bovine enzyme, whereas some differences were found in the amino acid composition of these enzymes. Buffalo and bovine enzyme possess similar but not identical structures. General proteolytic and milk-clotting activities of buffalo chymosin are also similar to those of bovine proteinase. pH-Optimum of its activity against hemoglobin lies at pH 4.0, somewhat higher than that for bovine chymosin, which indicates subtle differences in the functional properties of two enzymes.
Asunto(s)
Aminoácidos/análisis , Búfalos/metabolismo , Quimosina/aislamiento & purificación , Secuencia de Aminoácidos , Animales , Bovinos , Quimosina/química , Estabilidad de Enzimas , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Peso Molecular , Especificidad de la EspecieRESUMEN
Swine pepsin at pH 5 efficiently catalyzes a condensation between Z-Ala-Ala-Phe-OH and p-nitroanilides of Leu, Phe, Val, Ala and Arg that leads to formation of corresponding benzyloxycarbonyl-tetrapeptide p-nitroanilides with yields of 70-90%. These reactions are complicated by co-precipitation of pepsin and the reaction products that necessitates the use of a relatively high concentration of pepsin.
Asunto(s)
Oligopéptidos/biosíntesis , Pepsina A/metabolismo , Secuencia de Aminoácidos , Anilidas/química , Anilidas/metabolismo , Animales , Técnicas In Vitro , Datos de Secuencia Molecular , Nitrocompuestos/química , Nitrocompuestos/metabolismo , Oligopéptidos/química , PorcinosRESUMEN
Calf chymosin was shown to catalyse peptide synthesis optimally over the range pH 4-5, giving satisfactory yields of methyl esters or p-nitroanilides of benzyloxycarbonyl tetra- to hexa-peptides, provided that hydrophobic amino-acid residues form the new peptide bonds. The effectiveness of the enzyme depends also on the nature of adjacent amino-acid residues. As an aspartate-proteinase with a characteristic specificity pattern chymosin would be useful for the synthesis of middle-length peptides.
Asunto(s)
Quimosina/química , Péptidos/síntesis química , Secuencia de Aminoácidos , Animales , Bovinos , Química Orgánica/métodos , Datos de Secuencia MolecularRESUMEN
Calf chymosin catalyzes peptide synthesis optimally at pH 4-5 giving satisfactory yields of methyl esters or p-nitroanilides of benzyloxycarbonyl tetra- to hexapeptides, provided that hydrophobic amino acid residues form the new peptide bond. The enzyme efficiency depends also on the nature of adjacent amino acid residues. As an aspartyl proteinase with characteristic specificity pattern chymosin would be useful for synthesis of middle length peptides.
Asunto(s)
Quimosina/química , Péptidos/síntesis química , Secuencia de Aminoácidos , Animales , Catálisis , Bovinos , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Oligopéptidos/síntesis química , Oligopéptidos/química , Péptidos/químicaRESUMEN
It has been shown that in the course of equilibrium peptide synthesis pepsin gradually disappeared from the liquid phase due to its entrapment within a gel formed by the hexapeptide product, while retaining its activity. The inclusion into the precipitate was not specific for pepsin so far as inert proteins-lysozyme, ribonuclease A and carbonic anhydrase, when added to the reaction mixture, became also co-precipitated with the hexapeptide formed. It appears that co-precipitation of pepsin-an important factor limiting the enzyme efficiency, might be operative as well for other proteinases used to catalyze peptide synthesis.