[Modification of the histidine in rat skeletal muscle deaminase by diethylpyrocarbonate].

Diethylpyrocarbonate inactivated rat skeletal muscle AMP deaminase in 10 mM phosphate buffer, pH 6.5, at 23 degrees with the second order rate constant of 580 M-1.min-1.

[Subunit structure of AMP-deaminase from skeletal muscles].

AMP-deaminase was purified from skeletal muscle of rat by the affinity chromatography on phosphocellulose and gel-filtration on Sephadex G-200. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE) has shown three protein bands on each step of purification. One of them corresponds to the subunit of tetrameric AMP-deaminase molecule with molecular weight of 76 kDa and two others--to the protein subunit with molecular weight of 42 and 33 kDa.

[Effect of thiol reagents on cerebral glutaminase activity].

It has been shown that the glutaminase activity of brain mitochondrial fractions, which is stimulated by various activators, is completely abolished on 10 min preincubation with parachlormercurybenzoate, 5,5'-dithiobis-(2-nitrobenzoate), N-ethylmaleimide, iodoacetamid, CdCl2, ZnCl2 and CuCl2. With the purpose of elucidating the role of SH-groups in glutaminase activity we have studied the possibilities of preventing loss of enzyme activity by substrates and activators. We have shown that glutamine is effective only in the case of CuCl2.