Unknown

Dataset Information

0

Assay, purification, properties and mechanism of action of gamma-glutamylcysteine synthetase from the liver of the rat and Xenopus laevis.


ABSTRACT: 1. An improved radioassay for glutathione synthetase and gamma-glutamylcysteine synthetase was developed. 2. Xenopus laevis liver gamma-glutamylcysteine synthetase was purified 324-fold by saline-bicarbonate extraction, protamine sulphate precipitation, CM-cellulose and DEAE-cellulose column chromatography, and gel filtration. 3. Rat liver gamma-glutamylcysteine synthetase was purified 11400-fold by a procedure similar to that employed for the Xenopus laevis enzyme. 4. Rat liver gamma-glutamylcysteine synthetase activity was inhibited by GSH and activated by glycine. These effects, which were not found in the enzyme from Xenopus laevis, may have a regulatory significance. 5. Isotope-exchange experiments revealed fundamental differences in the partial reactions catalysed by the rat and Xenopus laevis synthetases. The enzyme from Xenopus laevis appears to follow a Bi Bi Uni Uni Ping Pong mechanism, with glutamyl-enzyme as intermediate before the addition of cysteine and the release of gamma-glutamylcysteine. The results for the rat liver enzyme are consistent with a Tri Tri sequential mechanism.

SUBMITTER: Davis JS 

PROVIDER: S-EPMC1177756 | biostudies-other | 1973 Aug

REPOSITORIES: biostudies-other

Similar Datasets

| S-EPMC21763 | biostudies-literature
| S-EPMC5613772 | biostudies-literature
| S-EPMC523444 | biostudies-literature
| S-EPMC1217934 | biostudies-other
| S-EPMC1220010 | biostudies-other
| S-EPMC8485494 | biostudies-literature
| S-EPMC4935901 | biostudies-literature
| S-EPMC3863412 | biostudies-literature
| S-EPMC1346807 | biostudies-literature
| S-EPMC1218650 | biostudies-other