Sex Pheromone of Rice Stem Borer; Purification and Chemical Properties

Bacillus vitellinus, a butirosin-producing organism, was shown to possess butirosin 3′-phosphotransferase catalyzing the phosphorylation of butirosin A into butirosin A 3′-phosphate.

The enzyme was purified about 1200-fold from the cell-free extract of the organism by ammonium sulfate fractionation, affinity chromatography on butirosin A-Sepharose 4B and two gel filtrations on Sephadex G–100.

The molecular weight of the enzyme was estimated to be about 30,000 by gel filtration. The pH optimum was between 6.7 and 8.8. Mg²⁺ was required for maximal activity and could be partially replaced by Co²⁺. ATP and GTP were effective phosphoryl donors. The enzyme catalyzed the phosphorylation of aminoglycoside antibiotics such as butirosin A, butirosin B, xylostasin, ribostamycin, neomycin, paromomycin, kanamycin A and kanamycin B. The Km values for butirosin A and ATP were 4.0 × 10^?6 m and 5.6 × 10^?5 m, respectively. The enzyme was strongly inhibited by p-chloromercuribenzoate, Ag⁺ and Hg²⁺, and was competitively inhibited by 3′-deoxybutirosin A.