Abstract
Membrane-bound L-sorbose dehydrogenase was purified from the membrane fraction of Gluconobacter melanogenus UV10. The reaction with 2, 6-dichlorophenolindophenol or phenazine methosulfate as acceptor was formulated as; L-sorbose + acceptor →-sorbosone + reduced acceptor.
The enzyme was purified by DEAE-Cellulose, DEAE-Sepharose, and Sephadex G-200 column chromatographies after differential solubilization with Triton X-100 and Tween 80, and appeared as a single band in a SDS-PAGE gel at the molecular weight of about 58, 000. It was most active at pH 7.0 and 48°C, and rather stable at around 7.0 in a buffer containing 200 mM L-sorbose, below 30°C. It showed high substrate specificity for L-sorbose, and its activity was stimulated by Fe3+ and Co2+, and inhibited by Cu2+, quinine, mono-iodoacetate, and sodium fluoroacetate.
