V.A. Khramov, A.I. Artyukhina

The given paper deals with the problem of precise detection of beta-galactosidase activity in human saliva. It is achieved by using a simple method of quantitative detection offered to use. The procedure of analysing bete-galactosidase activity of human saliva is described. This procedure is based on photometric detection of phenol which is released while synthetic substrate of phenyl-beta, D-galactopyranoside (phenylgalactoside)is hydrolysed. Phenol was detected by the famous Pauli-s reaction in our modification. In the course of the investigation the optimal composition of the incubation sample as well as the conditions of reaction procedure were determined. Galactosidase activity was determined as the difference between the extinction of the sample incubated with the substrate and that without substrate. The samles of human saliva in 14 healthy people with relatively favorable dental status were investigated. Based on this investigation it was determined, that specific activity of beta-galactosidase in human saliva of healthy people amounted from 0.9 to 2.5 ncat/ml (M ± m; 1,8 ± 0,2 ncat/ml). Kinetic parameters of the reaction were defined. Beta - galactosidase of human saliva is characterized by comparatively high relationship with synthetic phenylgalactoside: the seeming constant of Michaelis, determined by Linouiver-Berk method made 0.7 mmol/l, whilr the maximum speed (Vmax) was equal to 4.1 ncat/ml. It was determined that a number of natural carbohydrates (galactose, lactose, lactulose, saccharose, glucose, fructose, maltose) can inhibit the reaction of hydrolyzing phenylgalactoside, The inhibiting effect respectively made from 87% in galactose to 27% in maltose. The speed of utilizing carbohydrates by human saliva was studied by ortho-toluidine method. Galactose showed competitive type of inhibition. Inhibition constant equals to 0.02 mol/l.