小麦粉発酵性細菌Enterobacter cloacae GAOにおける乳酸脱水素酵素(LDH)の精製とその特徴について

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Enterobacter cloacae GAO, a leavening bacterium, was studied for its assimilation of organic acids contained in a culture broth. E. cloacae GAO produced lactic acid and formic acid therefore, the lactate dehydrogenase (LDH) of E. cloacae GAO may affect the production of hydrogen gas by the bacterium. We investigated the purification and characteristics of the lactate dehydrogenase from E. cloacae GAO. The last purification step resulted in the specific activity of the enzyme being increased 48.5-fold with a yield of 4.6%. The molecular weight of the purified enzyme was approximately 115,000 by gel filtration, being composed of four subunits each with a molecular weight 31,000 as evaluated by SDS-polyacrylamide gel electrophoresis. The optimum pH and temperature for the enzyme activity were 7.5 and 30℃ , respectively. The lactate dehydrogenase was stable at 40℃ and between pH 7 and 9, and the enzyme activity was strongly inhibited by Cu^lt2+gt and Mn^lt2+gt. The enzyme predominantly contained glutamic acid in its amino acid composition.
社団法人日本家政学会の論文
1997-07-15