[The heterogeneous character of protein modification during substitution of their amino groups. Acylation of alpha-chymotrypsin]. / Geterogennyi kharakter modifikatsii belkov pri zameshchenii ikh aminogrupp. Atsilirovanie al'fa-khimotripsina.

Thin-layer isoelectric focusing of chymotrypsin modified by stepwise acylation with acryloyl chloride or maleic anhydride revealed a high heterogeneity of modification products, with a maximal number of components near 50% of substituted amino groups. Disc electrophoresis failed to establish the products diversity and could not therefore be used for heterogeneity control. The activity of the modified enzyme towards proteins and low molecular weight substrates depended on the modification reagent and correlated with the electrostatic enzyme--substrate interaction. The low hydrolytic activity towards N-acetyl-L-tyrosine p-nitroanilide was due to the increase in the Michaelis constant; the value of the catalytic constant remained unchanged.

[Optimization of immobilization conditions for acid proteinase from Aspergillus awamori]. / Optimizatsiia uslovii immobilizatsii kisloi proteinazy iz Aspergillus awamori.

To optimize the immobilization conditions for acid proteinase from Aspergillus awamori by covalent binding through glutaraldehyde, experiments were carried out using the Box-Wilson method. The optimization process was assessed on the basis of absolute activity A, coefficient of activity retention gamma and their product A gamma. The following conditions can be recommended: glutaraldehyde concentration 50--60 mg/g, enzyme concentration not less than 40 mg/g, time of glutaraldehyde treatment 2--2.5 hrs, immobilization time 2 hrs, pH about 4.0, and temperature 35--40 degrees C. Under these conditions A=220--230 U/g, gamma = 23--24% Agamma = 5,000--6,000.

[Immobolization of beta-galactosidase on silochrome]. / Immobilizatsiia beta-galaktozidazy na silokhrome

Beta-Galactosidase (beta-D-galactoside galactohydrolase 3.2.1.23) from Curvularia inaequalis was immobilized by glutaric dialdehyde on gamma-aminopropyl triethoxysilane treated porous siliceous carrier silochrome. From the crude preparation with a specific activity of 3.1 U/mg immobilized beta-galactosidase with an activity of 113 U/g was obtained. The immobilized enzyme did not show significant changes in its enzymic properties. The column filled with the resultant preparation and used to hydrolyze lactose in milk whey maintained 50% of its initial activity after a 30-day work at 50 degrees C.