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In this paper, it was first shown that under various conditions of nitrogen supply therifamycin yield was positively correlated with the mycelial specific activity of glutaminesynthetase (GS), then the enhancing effect of glutamine, the product of GS, on rifamycin bio-synthesis was demonstrated with resting cell system. The stimulatory effect of glutaminewas more pronounced than that of glutamate, and not reduced by a GS specific inhibitor, DON.However, the increase in yield brought about by glutamate, and by asparagine was stronglyinhibited by this inhibitor. Glutamine-CO~(15)NH_2 and glutamato-α-~(15)NH_2 were synthesized andcompared for the incorporation of ~(15)N into rifamycin. It was found that the amide nitrogenwas incorporated to a much greater extent than the α-amino nitrogen, showing that glutaminewas a direct precursor of the nitrogen atom in rifamycin. In addition, synthesis of A-32(C_7N), an intermediate secreted by an inactive mutant rif 1, was also greatly stimulatedby glutamine, and the synthetic C_7N was found to be able to stimulate the biosynthesis ofrifamycin. Based upon the above results, the route of incorporation of nitrogen atom into rifamycinis summarized as follows:  相似文献   
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力复霉素生物合成中氮原子的参入途径   总被引:1,自引:0,他引:1  
本文报道力复霉素产量与谷氨酰胺合成酶(GS)的正相关性,进而在洗涤菌体实验中证明谷氨酰胺促进力复霉素合成的作用远比谷氨酸显著,而这一促进作用不受GS专一性抑制剂DON的抑制,其它氨基酸如谷氨酸门冬酰胺的促进作用则受到这一抑制剂的抑制。谷氨酰胺-CO~(15)NH_2与谷氨酸-α-~(15)NH_2参入到力复霉素的比较实验指出,前者是力复霉素更直接的前体。再者,A-32(C_7N)的合成受谷氨酰胺促进,而人工合成的A-32(C_7N)又能促进力复霉素的合成。根据以上结果,本文提出了力复霉素分子中氮原子参入的途径。  相似文献   
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