Biosynthesis of Streptomycin.

dTDP-L-dihydrostreptose:streptidine-6-phosphate dihydrostreptosyltransferase, an enzyme in- volved in the biosynthesis of streptomycin, has been purified from Streptomyces griseus to near homogeneity by a six-step procedure involving chromatography on streptidine-6-phosphate- Sepharose. By gel filtration the apparent Mr of the enzyme was found to be about 63000. The subunit Mr found on sodium dodecylsulfate gels is about 35000. 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-α-L-dihydrostreptose(1→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 50h of fermentation, just before appearance of streptomycin in the medium. [ABSTRACT FROM AUTHOR]