| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1992: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1991: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Research Abstract |
Teleocidins are potent tumor promoters produced by actinomycetes. Hitherto, total syntheses of teleocidins and their fundamental structure, (-)-indolactam-V (ILV), have been intensively investigated. However, more convenient syntheses, especially improvement of introduction of an amino group into position 4 of the indole ring, is desirable from the view point of synthesizing various indolactam congeners for structure-activity studies.
We demonstrated that ILV was biosynthesized from L-Trp, L-Val and L-Met via N-Me-L-Val-L-Trp-ol using Streptoverticillium blastmyceticum NA34-17. Since N-Me-L-Val-L-Trp-ol can be chemically synthesized without difficulty, utilization of the microbial cyclization enzyme would be a convenient synthetic method of various ILV analogues. We metabolized ca. 20 seco-compounds and obtained ca. 15 ILV congeners, which had various L-amino acids instead of L-Val in ILV, several substituents on position 6 of ILV, or an ethyl group at position 13 instead of the methyl group in (-)-indolactam-Nva. These ILV congeners were examined for two biological tests related to tumor promotion. They were binding to the 12-O-tetradecanoylphorbol-13-acetate receptor and stimulation of radioactive inorganic phosphate incorporation into phospholipids of HeLa cells. The results indicated that the hydrophobicity of the substituents at positions 6 and 12 increased these activities, and that the steric requirement at position 13 was very high.
We furthermore attempted to isolate this cyclization enzyme using N-Me-L-Ile-L-Trp-ol whose cyclization product rarely occurred naturally, and whose cyclization yield was very high. Though the enzyme activity was detected in the intact mycelia, we could not detect any activity in the cell-free system which was prepared by sonication or freezing with liquid nitrogen.
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