Purification and Characterization of Glutaredoxin from Cryptococcus neoformans

초록

Glutaredoxin, also known as thioltransferase, was purified from Cryptococcus neoformans by procedures including DEAE-cellulose ion exchange chromatography, Q-Sepharose ion-exchange chromatography, and gel filtration on Sephadex G-50. Its purity was confirmed by SDS-polyacrylamide gel electrophoresis and its molecular weight was estimated to be 12,000 Da. The purified enzyme has a Km value of 1.03 mM with 2-hydroxyethyl disulfide as a substrate. The enzyme also utilizes L-sulfocysteine, L-cystine, and bovine serum albumin as substrates in the presence of reduced glutathione. The enzyme has Km values of 0.34-2.50 mM for these substrates. It was greatly activated by thiol compounds such as reduced glutathione, dithiothreitol, L-cysteine and β-mercaptoethanol. It is partially inactivated at 60°C or higher temperatures. It plays an important role in thiol-disulfide exchange in Cryptococcus neoformans.