RESUMEN
The activity and stability of native subtilisin 72, its complex with poly(acrylic acid), and subtilisin covalently attached to poly(vinyl alcohol) cryogel were studied in aqueous and organic media by hydrolysis of specific chromogenic peptide substrates. Kinetic parameters of the hydrolysis of Glp-Ala-Ala-Leu-pNA by native subtilisin and its complex with poly(acrylic acid) were determined. Based on the comparative study of stability of native and modified subtilisins in media of various compositions, it was established that covalent immobilization of subtilisin on poly(vinyl alcohol) cryogel is the most effective approach to improve enzyme stability in water as well as in mixtures with low water content.
Asunto(s)
Bacillus subtilis/enzimología , Proteínas Bacterianas/química , Enzimas Inmovilizadas/química , Péptidos/química , Subtilisinas/química , Resinas Acrílicas , Estabilidad de Enzimas , Cinética , Alcohol Polivinílico , Subtilisinas/aislamiento & purificaciónRESUMEN
The catalytic efficiencies of native subtilisin, its noncovalent complex with polyacrylic acid, and the subtilisin covalently immobilized in a cryogel of polyvinyl alcohol were studied in the reaction of peptide coupling in mixtures of organic solvents with a low water content in dependence on the medium composition, reaction time, and biocatalyst concentration. It was established that, in media with a DMF content > 80%, the synthase activity of modified subtilisins is higher than that of the native subtilisin. The use of N-acylpeptides with a free carboxyl group was found to be possible in organic solvents during the enzymatic synthesis catalyzed by both native and immobilized subtilisin. A series of tetrapeptide p-nitroanilides of the general formula Z-Ala-Ala-Xaa-Yaa-pNA (where Xaa is Leu, or Glu and Yaa is Phe or Asp) was obtained in the presence of immobilized enzyme in yields of 70-98% in DMF-MeCN without any activation of the carboxyl component and without protection of side ionogenic groups of polyfunctional amino acids.