SULPHATASES (synonym of sulfohydrolase; KF 3.1.6...) — enzymes of a class of hydrolases, a subclass of esterases, catalyze hydrolytic decomposition of sulphuric acid ethers. In a human body and animal S. play an important role in exchange steroid hormones (see), lipids (see), glikozaminoglikan and other connections. Genetic defects in S.'s synthesis (e.g., arylsulphatases A and B, an alpha - L - iduronosulfatazy, geparansulfataza, etc.) are the reason of heavy hereditary enzymopathies (see. Glikozidoza ; Mukopolisakharidoza ).
The most studied enzymes among S. are arylsulphatases (KF 22.214.171.124), eurysynusic in animal and vegetable fabrics. At a liver of mammals there are 3 types of arylsulphatases — arylsulphatase A, a pier. weight (weight) 107 000, arylsulphatase B, pier. the weight 45 000, and S. Arilsulfataza's arylsulphatase And yes In are localized in lysosomes (see), are easily solubilized (see. Solubilization ), are similar among themselves on substrate specificity and sensitivity to inhibitors. Arylsulphatase C is strongly connected with membranes of an endoplasmic reticulum (a granular cytoplasmic reticulum) and is badly solubilized. Reagents on carbonyl groups inhibit all three arylsulphatases, cyanide suppresses activity only of S. Arilsulfataza's arylsulphatase And yes In are found in a blood plasma of the person (activity of these enzymes normal makes: 0,87± 0,23 nkat/l — substrate 4-metilum-belliferilsulfat, 37 °; 0,58±0,13 nkat/l — substrate tg-nitroka-tekholsulfat, 37 °; 1 rolled — kat — on the SI system 1 mol/sec. is equal). Arylsulphatases A and B are present also at urine, synovial and cerebrospinal liquids of the person.
At the person and other mammals, and also the sterolsulfataza is found in mollusks (KF 3.1. 6. 2). High activity of this enzyme is characteristic of a liver, adrenal glands, seed bubbles and ovaries of mammals. Activity of a sterolsulfataza in a placenta of the person is especially high. Believe that the sterolsulfataza participates in formation of free steroids (see) in the course of their biosynthesis from cholesterol (see) and pregnenolona. In many tissues of the person and other mammals tserebro-zidsulfataza are found (KF 3. 1. 6. 8.), substrate to-rykh are sulfatides (see).
Definition of activity of S. is based on measurement of amount of the sulfate which is chipping off under the influence of enzyme from substrate specific for investigated by Page. During the definition of activity of arylsulphatases A and B as substrates use 4-metilumbelliferilsulfat (a flyuorimetrichesky method) or n-nitrokatekholsulfat (colorimetric method) and on intensity of fluorescence (or colourings) chipped off as a result of fermental reaction 4-metilumbel-liferona (or n-nitrocatechin) judge activity of enzyme.
Bibliography: Dickson M. and At e E. Enzymes, the lane with English, t. 1 — 3, M., 1982; The Nomenclature of enzymes, the lane with English, under the editorship of A. E. Braunstein, M., 1979; Pokrovsky A. A. and V. A Tu-telyan. Lysosomes, M., 1976; Wissenschaftliche Tabellen Geigy, hrsg. v. A. G. Geigy, S. 167, Basel, 1979.
I. Ya. Kon, V. A. Tutelyan.