An ultramicro assay for leucine aminopeptidase activity in biological materials by phosphorimetry.

An optimized assay of alanine aminopeptidase activity in urine.

Elaboration of an optimized kinetic test for urinary alanine aminopeptidase at 37 degrees C is described. As final concentrations, 50 mmol/L tris(hydroxymethyl)aminomethane x HCl buffer, pH 7.8, and 2 mmol/L alanine-4-nitroanilide are proposed. Five- to sixfold activitiy is obtained as compared with a generally used test procedure. Coefficients of variation for the method (within-run and betwee...

An ln vivo Assay for Biological Activity of Synthesized Recombinant Human Growth Hormone

Leucine aminopeptidase fragments from an ascites tumor.

By 1946 (4) about 35 enzymes had been isolated and crystallized, and the controversy over their chemical nature was resolved with the conclusion that all enzymes contained a protein component essential for their activity. In 1951, however, Binkley (5-7) claimed to have purified highly active peptidases which analyzed as polynucleotides and were free from protein. His procedure was designed to e...

Leucine Aminopeptidase (Bovine Lens)

The stability to pH and denaturing agents of crystalline leutine aminopeptidase (bovine lens) (EC 3.4.1.1) is reported. The native enzyme exhibited a molecular weight of 327,000. In 7 M urea below pH 3 and in 23.7 M guanidinium chloride below pH 8.5, both leucine aminopeptidase and its reduced and carboxamidomethylated derivative exhibited a molecular weight on equilibrium centrifugation of 54,...

Leucine Aminopeptidase (Bovine Lens)

Spark emission and atomic absorption spectroscopy of crystalline leucine aminopeptidase (bovine lens) (EC 3.4.1.1) shows the presence of 2 zinc atoms per subunit molecular weight of 54,000 (12 zinc atoms per oligomer of 320,000). Removal of zinc by dialysis yields a zinc-free product with no enzymatic activity which upon readdition of Zn2+, regains full activity with the concomitant binding of ...