1) Effect of Blasticidin S on glycolysis in
Piricularia oryzae was-examined by measuring lactic acid according to the method of Backer Sammerson, using the suspension of washed mycelium prepared by the method described previously. The glycolysis was almost not inhibited by Blasticidin S, but was remarkably inhibited by phenyl mercuric acetate and monoiodoacetate.
2) Eflect of Blasticidin S on succinic dehydrogenase in cell free extract of the mycelium of
Piricularia oryzae was examined by the method in which TTC reduction was measured by the Thunberg technique. Blasticidin S had no significant influence on the succinic dehydrogease.
3) Effect of Blasticidin S on the oxidative phosphorylation by mitochondrial fraction from rat liver was examined. Oxygen consumption was measured manometrically and phosphorylation was estimated by the determination of inorganic phosphate. The oxygen uptake and the oxidative phosphorylation by the rat liver mitochondria were not affected by Blasticidin S, but both reactions were inhibited by phenyl mercuric acetate and Blastmycin.
4) Effect of Blasticidin S on the turnover of inorganic phosphate by respiring mycelium of
Piricularia oryzae was studied with the aid of exogenous inorganic phosphate labelled with
32P.
32P from labelled phosphate in the medium was taken up more into the nucleic acid fraction than into the phospholipid or the protein fraction of the mycelium. Each fraction was isolated by the method of Schneider. It was found that the incorporation of
32P into each of the fractions was not influenced by Blasticidin S.
5) Addition of
14C-glutamic acid to the suspension of the mycelium above mentioned resulted in the incorporation of
14C into the mycelium. Since
14C-glutamic acid was incorporated more into the protein fraction than into the nucleic acid or the phospholipid fraction, the incorporation was taken as a measure of examinig protein synthesis. The incorporation into the protein fraction of the mycelium was strongly inhibited by Blasticidin S at a concentration of 1μ
g/ml. Because this inhibitory concentration was almost equal to the minimum growth inhibitory concentration (0.1-1.0μ
g/ml), it seemed that the inhibition of protein synthesis was a primary effect of Blasticidin S on the metabolism of
Piricularia oryzae.
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