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Title: Studies on the biosynthesis of the modified-peptide antibiotic, nosiheptide

Thesis/Dissertation ·
OSTI ID:6592244

The biosynthesis of nosiheptide, a highly modified-peptide antibiotic, was studied by feeding /sup 14/C- and /sup 13/C-labeled precursors to the producing organism, Streptomyces actuosus. To this end, methods were developed for the fermentation of S. Actuosus, and the isolation of nosiheptide. Nosiheptide was produced in a synthetic medium at levels of 175 to 200 mg/L. In addition, a HPLC method was developed for rapid and accurate assay of nosiheptide in fermentation broths. During the fermentation studies, nosiheptide production was found to be inhibited by tryptophan, cysteine, ammonia, and phosphate. Feeding experiments with DL-(3-/sup 13/C)cysteine, L-(3-/sup 13/C)serine, DL-(1-/sup 13/C)serine, L-(CH/sub 3/-/sup 13/C)methionine, and L-(2,1'-/sup 13/C/sub 2/)tryptophan uncovered the biosynthetic precursors of the residues in nosiheptide. The double-quantum NMR technique known as INADEQUATE was used to analyze nosiheptide biosynthesized from (U-/sup 13/Cnumber)glycerol. This experiment permitted unambiguous /sup 13/C-NMR assignments to be made, as well as elucidation of the biochemically maintained /sup 13/C-/sup 13/C connectivities in the conversion of the labeled glycerol to nosiheptide. Making some reasonable assumptions, a logical peptide precursor of nosiheptide is proposed: H/sub 2/N-ser-cys-thr-thr-cys-glu-cys-cys-cys-ser-cys-ser-CO/sub 2/.

Research Organization:
Ohio State Univ., Columbus (USA)
OSTI ID:
6592244
Resource Relation:
Other Information: Thesis (Ph. D)
Country of Publication:
United States
Language:
English