BIOORGANIC CHEMISTRY OF MICROBIAL METABOLITES. PART ONE: BIOSYNTHESIS OF CHLOROTHRICIN. PART TWO: BIOSYNTHESIS OF APLASMOMYCIN. PART THREE: STERIC COURSE OF THE 5-ENOLPYRUVYLSHIKIMATE-3-PHOSPHATE SYNTHETASE REACTION. PART FOUR: STRUCTURE ELUCIDATION OF BOROMYCIN ANALOGUES AND CONFORMATIONAL ANALYSIS OF DESVALINOBOROMYCIN (CHIRAL METHYL, METHODOLOGY)
Abstract
I. The origin of carbon atoms 22, 23 and 24 of chlorothricin was established to be phosphoenolpyruvate from feeding experiments of {1,2,3-('13)C(,3)}glycerol and (2R)-{1-('2)H(,2)}glycerol. Metabolic pathways from succinyl-Co A to methylmalonyl-Co A were distinguished by {1,2-('3)C(,2)}succinate feeding experiment. The result indicates that the two propionate-derived units of chlorothricin are formed exclusively by the succinyl-Co A-methylmalonyl-Co A rearrangement with rapid equilibration between succinyl-Co A and free succinate. The steric course of the removal of the OH group from C-2 of glucose was established as an inversion of configuration at C-2 by feeding {2-('2)H}glucose. II. The mode of conversion of glycerol into the starter unit for the polyketide chain making up aplasmomycin was studied using ('2)H-NMR spectroscopy and chiral methyl group methodology. The results indicate that phosphoenolpyruvate or phosphoglyceric acid must be the starter unit. The stereochemistry of the C-methylation reaction in aplasmomycin formation in vivo was studied by feeding stereospecifically ('2)H and ('3)H labeled precursors. The results indicate that racemization occurs during the transformation of serine to methionine. III. Chorismate biosynthesized from (1R,2R)-{1-('2)H,('3)H}glycerol was converted to racemic lactate which were resolved and analyzed for the methyl group configuration. The configuration for the side chain double bond of the deuterated tritiated chorismate, was determined to be E. Therefore, the addition and elimination steps in the ESP synthetase reaction proceed with opposite stereochemistry. IV. Two boromycin-like compounds from the culture of Streptomyces sp. MA 4423 were identified as N-acetylboromycin and N-formylboromycin. A large number of distinguishable protons of the ('1)H-NMR spectra of boromycin and desvalinoboromycin were assigned. Comparison of dihedral angles calculated from the coupling constants of desvalinoboromycin to the measured value from X-ray indicate that the solution conformation of desvalinoboromycin in chloroform is very similar to that of the crystalline state.
Degree
Ph.D.
Subject Area
Organic chemistry
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