[Function of angiotensin-converting enzyme on matrices]. / Funktsionirovanie angiotenzin-prevrashchaiushchego fermenta na matritsakh.

The binding of the angiotensin-converting enzyme from bovine lung on BrCN-activated Sepharose, CH- and AH-Sepharoses as well as on AH-Sepharose via the carbohydrate fragment of the glycoprotein molecule modulates the possible microenvironment of the enzyme in vivo. It has been shown that the close interaction of the enzyme with the carbohydrate matrix may increase the absolute values of catalytic constants for the hydrolysis of certain substrates. The binding of the angiotensin-converting enzyme to the matrices markedly changes the enzyme activation by chloride ions by causing a shift in the activity optima towards lower activator concentrations.

[Physico-chemical characteristics of angiotensin-converting enzyme from the bovine lung]. / Fiziko-khimicheskie kharakteristiki angiotenzin-prevrashchaiushchego fermenta iz legkikh byka.

The angiotensin-converting enzyme from bovine lung was isolated by chromatography with a 25-30% yield and purified 2200-2600-fold. The active molecule concentration in the enzyme preparations was 70-100% as could be judged from titration by inhibitor SQ 20,881. The molecular mass of the enzyme according to electrophoretic data is about 132 kDa; the maximal radius of the enzyme molecule as determined by electron microscopy is 68 +/- 9 A. Five enzyme isoforms with pI of 4.85, 4.7, 4.54, 4.38 and 4.3, respectively, were identified. The kinetic parameters of hydrolysis of three synthetic peptide substrates and the constants of activation of the substrate (Z-Phe-His-Leu) hydrolysis by chloride anions were determined.