Biosynthesis of Streptomycin. Purification and Properties of a dTDP-l-Dihydrostreptose: Streptidine-6-phosphate Dihydrostreptosyltransferase from Streptomyces griseus

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Abstract
DTDP-L-dihydrostreptose: streptidine-6-phosphate dihydrostreptosyltransferase, an enzyme involved in the biosynthesis of streptomycin, was purified from S. griseus to near homogeneity by a 6-step procedure involving chromatography on streptidine-6-phosphate-Sepharose. By gel filtration the apparent MW of the enzyme was found to be about 63,000. The subunit MW found on sodium dodecylsulfate gels is about 35,000. The transferase is dependent on Mn2+ or Mg2+ ions. Co2+ is as effective as Mg2+. From the substrates tested only streptidine 6-phosphate was an acceptor for dihydrostreptose in the synthesis of O-.alpha.-L-dihydrostreptose(1 .fwdarw. 4)-streptidine 6-phosphate. No activity was found with streptidine, 2-deoxystreptamine and 4-deoxystreptamine. The activity of the transferase in the course of fermentation runs parallel to the activity of dTDP-dihydrostreptose synthase and reaches a maximum after around 50 h of fermentation, just before appearance of streptomycin in the medium.