[Properties of urease immobilized on silochrome by means of disulfide bonds].

Grafting of SH-groups to the silica surface through the hydrolytically stable Si-C-bond is conducted by gamma-mercaptopropyltrimethoxysilane. After 2,2'-dithiobis-p-nitrobenzoic acid (Ellman's reagent) activation of sulphydryl groups urease of microbial origin was immobilized by these carriers. Certain properties of the preparations obtained were studied. The Km of the enzyme during nonporous silicon aerosil immobilization is shown to remain without considerable changes. The found variations in properties of silochrome-immobilized urease are caused by the diffusion inhibition for the substrate and product of the reaction observed even when the substrate concentration is two orders higher than Km.