Gamma-glutamyl hydrolase (GH), which hydrolyses the gamma-glutamyl conjugates of folic acid, is a key enzyme in the maintenance of cellular folylpolyglutamate concentrations. The catalytic mechanism of GH is not known. Consistent with earlier reports that GH is sulphydryl-sensitive, we found that recombinant human GH is inhibited by iodoacetic acid, suggesting that at least one cysteine is impo...

in this study, the chemical factors effect of metal ions, surfactant, oxidizing agents and enzyme inhibitors on the activity of trypsin and chymotrypsin of rainbow trout fry were considered. the results showed that k+ and na+ had not significant decrease on trypsin and chymotrypsin activity than did those from control (p>0.05). ca2+ and mg2+ showed a significant increase in activity of trypsin ...

1. The kinetics of the reaction which takes place between glycine and iodoacetic acid was studied by means of the polarographic method. 2. On the basis of kinetic equations, evidence was obtained that (a) The reaction proceeds in two steps in which the hydrogens of the amino group are consecutively replaced by the acetyl radicals, the velocity constants being in the ratio 2:1. (b) Only the anio...

The present communication describes the elucidation of the sequence of amino acid residues around the single half-cysteinyl residue (Liu, Neumann, Elliott, Moore, and Stein (1)) of the proteinase derived from the zymogen produced by Group A hemolytic streptococci (Elliott (2)). This -SH group is essential for the proteolytic activity of the reduced enzyme; therefore, as a working hypothesis, th...

Investigations of human red blood cells show that a cytoplasmic protein called calpromotin is involved in the regulation of calcium-activated potassium transport. Calpromotin associates with the membrane in the presence of calcium and undergoes a chemical transformation. High performance gel filtration and gel electrophoresis show that the cytoplasmic and membrane-bound calpromotin can exist in...

1. The rate of the saponification of iodoacetic acid in sodium hydroxide and alkaline buffer solutions yielding glycollic acid was measured by means of Heyrovský's polarographic method. 2. From the bimolecular velocity constants, increasing with the ionic strength of the solution, the Brönsted factor, F, which characterizes the primary salt effect, was calculated. 3. In the borate buffer soluti...