S. Ratner
1957
Citations
0
Influential Citations
10
Citations
Journal
Methods in Enzymology
Abstract
Publisher Summary Argininosuccinic acid can be prepared enzymatically by the splitting enzyme, which catalyzes the reversible reaction: argininosuccinic acid⇋arginine+fumaric acid. With high concentrations of arginine and fumaric acid, about 75% of the substrates is converted to argininosuccinic acid when equilibrium is reached. For high purity and yield of argininosuccinic acid, it is desirable that the splitting enzyme be free of arginase and fumarase. Pig kidney is an excellent enzyme source for this purpose. The method of estimation, which is highly specific, depends on the observation that cleavage to arginine, and then to urea, proceeds to completion in dilute solution, in the presence of excess splitting enzyme and excess arginase. In procedure, an aliquot containing is added to the incubation mixture of buffer. Splitting enzyme is omitted from one tube to check that the material is free of arginine. The tubes are incubated at 38 ° for 1 hour, 0.5 ml. of 25% trichloroacetic acid is added, and urea is then estimated colorimetrically in 0.5 ml. of the filtrate as in the assay of the splitting enzyme. The results are expressed as micromoles per milligram of the barium salt.