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Biosynthetic and structural studies of neomycin and berninamycin

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Title: Biosynthetic and structural studies of neomycin and berninamycin
Author(s): Lau, Raymond Chung Man
Doctoral Committee Chair(s): Rinehart, Kenneth L., Jr.
Department / Program: Chemistry
Discipline: Chemistry
Degree Granting Institution: University of Illinois at Urbana-Champaign
Degree: Ph.D.
Genre: Dissertation
Subject(s): Chemistry, Organic Chemistry, Pharmaceutical
Abstract: ($\sp{13}$C$\sb6$) Glucose (3) was supplemented to seven-days old resting cells of neomycin B-proucing S.fradiae. The $\sp{13}$C NMR spectra of the enriched neomycin B (2) showed complex coupling patterns which suggested that 3 is not incorporated as an intact C$\sb6$ unit into the carbon skeleton of 2. These complex splitting patterns of 2 can be explained when 3 is first shunted through the pentose phosphate pathway to form primary metabolites of different carbon length. Some of these metabolites are then reconstituted back to six-carbon unit for the biosynthesis of 2.Two-dimensional NMR and FAB MS/MS studies have confirmed the structure of berninamycin A as proposed by Abe et al. Biosynthetic studies with $\sp{13}$C enriched amino acids showed that the dehydroalanines units were formed by dehydration of serine, the oxazoles were formed by condensing a threonine unit with a dehydrothreonine/dehydroalanine, the thiazole was formed by combining a cysteine with a dehydroalanine, and the biosynthesis of the pyridine ring was similar to the piperidine/hydroxypyridine ring formation in thiostrepton and nosiheptide. The biogensis of berninamycin A was discussed.Berninamycins B, C, and D were isolated by reverse-phased HPLC from S.bernensis. The structures of berninamycins B and D were studied with $\sp{13}$C NMR and FAB mass spectrometries. Berninamycin B was found to be deoxyberninamycin A with a valine unit instead of the $\beta$-hydroxyvaline unit of berninamycin A. Berninamycin D was found to have two less dehydroalanine units attached to the carboxyl carbon of the pyridine ring moiety. The structure of berninamycin C was postulated to have one less dehydroalanine unit attached to the carboxyl carbon of pyridine based on FABMS result. The biogeneses of these minor metabolites were discussed.
Issue Date: 1990
Type: Text
Language: English
URI: http://hdl.handle.net/2142/23172
Rights Information: Copyright 1990 Lau, Raymond Chung Man
Date Available in IDEALS: 2011-05-07
Identifier in Online Catalog: AAI9114306
OCLC Identifier: (UMI)AAI9114306
 

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