GALACTOSIDASES — the galaktozidgalaktogidrolaza, enzymes belonging to the class of hydrolases, a subclass glikozidaz; chip off a galactose from various substrates — oligosaccharides, polysaccharides and glycoconjugates (e.g., glycolipids, glycoproteins etc.). Split also synthetic substrates containing a galactose, napr, nitrophenyl and paranitrofenilgalaktozida.
Are divided for Alpha (KF 18.104.22.168) and Beta (KF 22.214.171.124).
Are eurysynusic in the nature. They are found in bacteria, plants and in various bodies and biological liquids of animals and the person.
Exist in various molecular forms, to-rye differ on properties of substrate specificity. So, an optimum of pH at Alpha and β-Γ. various origin from 4,0 to 7,0 fluctuates. Nek-ry molecular forms β-Γ. chip off a galactose from gangliosides, but do not chip off it from galaktotserebrozid etc. G. are in various subcellular structures — mitochondrions, lysosomes, a hyaloplasma and subcellular membranes. For the person and mammals one of β-Γ has great value. — lactase of a mucous membrane of intestines. Disturbance of synthesis of this enzyme is the reason of an inborn disease of children — a hereditary lactose intolerance of milk (see. Milk , dairy products). For treatment of this disease lactases use drugs, to-rye previously add to food. Recently the way of a transmission of milk through columns with the connected lactase is offered. Such milk instead of lactose contains the hydrolyzed sugar — glucose and a galactose. Various G.' insufficiency in a liver, a brain and other human organs is the reason of many heavy hereditary glycolipidoses. At a gangliozidoza of hypermarket 1 , at Krabbe's disease and a laktozilkeramidoza are absent various β-Γ., and at Fabri's disease — α-@ For diagnosis of these diseases at patients and at heterozygous carriers of diseases define G.'s activity in fibroblasts of skin. Prenatal diagnosis of these diseases is based on definition of activity of various G. in an amniotic fluid during a certain period of fetation.
Drugs β-Γ., received from yeast and pleseny, find application in the food industry and agriculture.
See also Hydrolases .
Bibliography: Dickson M. and Webb E. Enzymes, the lane with English, page 196, etc., M., 1966; To r e of t about in and the p B. L. Fundamentals of phytochemistry, page 248, etc., M., 1971; M and r d and sh e in G. P. Biochemical problems of medicine, page 45, M., 19 75, bibliogr.; D e at R. M. and. P of i d h an in J. Century of Biochemistry of α-galactosidases, Advanc. Enzymol., v. 36, p. 91, 1972; The enzvmes, ed. by P. D. Boyer a. o., v. 4, p. 409, N. Y. — L., 1960.
T. H. Evreinona