ENZYMATIC CONVERSION OF DETHIOBIOTIN TO BIOTIN IN CELL-FREE-EXTRACTS OF A BACILLUS-SPHAERICUS BIOB TRANSFORMANT

The activity of biotin synthase, responsible for biotin synthesis from dethiobiotin, was demonstrated in a completely defined reaction mixtu re with cell-free extracts of a Bacillus sphaericus bioB transformant. Among the sulfur compounds tested, only S-adenosyl-L-methionine was a ctive, while L-methionine and L-cysteine had no significant effect. Pr otein concentrations higher than 15 mg/ml in the reaction mixture were needed to detect biotin synthase activity. When dialyzed cell-free ex tracts were used for the reaction, NADH, NADPH, or FAD among the well- known cofactors tested enhanced the activity, and Fe2+, Mn2+, and Ca2 among the metal ions tested also had some effects.