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1988
Journal Article
Titel
Selenium increased hydrogenase expression in autotrophically cultures Bradyrhizobium japonicum and is a constituent of the purified enzyme.
Alternative
Selen steigert die Expression der Hydrogenase in autotroph kultivierten Bradyrhizobium japonicum und ist ein Bestandteil des gereinigten Enzyms
Abstract
We have investigated the effect of added selenite on autotrophic growth and the time course of hydrogen oxidation derepression in Bradyrhizobium japonicum 122 DES cultured in a medium purified to remove selenium compounds. In addition hydrogenase was purified to near homogeneity and examined for the specific incorporation of Se into the enzyme. The addition of Se at 0.1 myM significantly increased total cell protein and hydrogenase derepression by 133 %, whereas VO3, AsO2 high 2 minus, SO2 high 2 minus, and TeO3 high 2 minus failed to substantially affect hydrogenase derepression. During the final chromatographic purification of hydrogenase, a striking coincidence in peaks of protein content, Se readioactivity, and hydrogenase activity of fractions was obtained. The total Se content expressed per milligram of protein increased manyfold during the purification procedure. The mean Se content of the purified hydrogenase was 0.56 plus minus 0.13 molof Se per mol of enzyme. These results in dicate that Se is an important element in the H2 metabolism of B. japonicum and that hydrogenase from B. japonicum is a seleno protein.