| C-1027 is a novel antitumor antibiotics produced by Streptomyces globisporus C-1027 which was isolated from the soil in Hubei, China. Its antitumor activity is 1,000 folds higher than adriamycin which is commonly used in clinic. The structure of C-1027 is composed of an acidic apoprotein and an enediyne chromophore with non-covalently binding. Apoprotein contains 110 amino acids, which stabilize the chromophore but has not antitumor activity. The chromophore consists of β -tyrosine, bensoxazolinate, deoxy aminosugar and enediyne structure, which is essential for antitumor bioactivity. The mechansim is that binding of enediyne core structure with the loop of double strand DNA, then absorbing hydrogen atoms from deoxyriboses after forming a transient benzenoid diradical by electron rearrangement to cleave DNA.C-1027 is a good research object for scientists, because of its novel structure, high antitumor activity and fascinating modes of action. Many reports were published about C-1027, but nothing for biosynthesis enzymes. 75kb C-1027 biosynthesis gene cluster containing 33 ORFs was first cloned from S. globisporus C-1027 by Dr. Liu, who confirmed 10 ORFs invloved in C-1027 biosynthesis with gene disruption and complement experiments. It is necessary to characterize the enzymes coded by ORFs for studing C-1027 biosynthesis pathway. In this paper ORF24 and ORF4 have been studied.MW of ORF24 for C-1027 biosynthesis gene cluster is 1620bp coding 540 amino acids. Protein coded by ORF24 is homologous to histidine ammonialyase or phenylalanine ammonialyase from various source. For ammonialyase the reaction is reversible, we deduce that ORF24 code the aminomutase catalizing α -tyrosine to β -tyrosine which involved in the biosynthesis of β -tyrosine for C-1027. To identify the function of ORF24, ORF24 was cloned into plasmid pET-30a to be induced expressed by IPTG which is in E. coli BL21. SDS-PAGE showed that there was a new band with MW 65KD the same as expectation.
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