THE BIOSYNTHESIS OF SPARSOMYCIN - FURTHER INVESTIGATIONS OF THE BIOSYNTHESIS OF THE URACIL ACRYLIC-ACID MOIETY

Precursor incorporation experiments have ruled out the involvement of N'-formylkynurenine in the biosynthesis of the uracil acrylic acid moi ety of sparsomycin. An enzyme has been partially purified from the spa rsomycin-producer that catalyzes the synthesis of the uracil acrylic a cid from a pyrimidine acrylic acid previously shown to be a sparsomyci n precursor. The enzymatic synthesis of the uracil acrylic acid requit es NAD(+), a result which indicates that the mechanism of the uracil a crylic acid synthase is similar to that of inosine-5'-monophosphate de hydrogenase. Analog studies demonstrate that the enzyme lacks rigid su bstrate specificity.