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Abstract

The nutritional deficiency of chromium has been linked with
impaired glucose tolerance, and more recently has been implicated in
cardiovascular disease. It was believed that a biologically potent
form of chromium existed as a coordination complex with nicotinic acid
and various amino acids. The biologically active chromium complex was
termed glucose tolerance factor (GTE) due to the curative effect on rats
raised on a chromium deficient diet resulting in impaired glucose
tolerance. The most studied source of GTE has been brewers' yeast
although little has been learnt regarding the structure of GTE. The
aim of this thesis was to isolate and characterize GTF.
An existing in vitro assay system for GTE has been developed
and is reported in this thesis. The assay was based on the anaerobic
oxidation of 14 C-glucose by yeast (Saccharomyces cerevisiae) and its
stimulation by GTF.
Brewers' yeast was used as a starting material for the isolation
of GTE. A defined synthetic Medium was eventually used for yeast culture,
in order to establish that GTF was produced by yeast and not derived from
culture medium components. GTF was isolated from yeast grown in synthetic
medium and in higher yield when chromium was present. Low levels of
chromium were found to inhibit yeast growth.
A biologically active cationic fraction extracted from yeast
was purified by chromatography. Nuclear Magnetic Resonance spectroscopy
and other instrumental techniques indicated that the isolated material
was a small lysine peptide devoid of chromium which could be likened to
a class of basic hypoglycemic, agents.
It was concluded that, as recent clinical trials reported
in the literature indicated a division between the effect of chromium
supplementation, and supplementation with high chromium yeast, GTF
isolated from yeast grown in presence of chromium represents an interesting
hypoglycemic agent.

Item Type:	Thesis - Unspecified
Authors/Creators:	Davies, Diana May
Keywords:	Glucose, Chromium in animal nutrition
Copyright Holders:	The Author
Copyright Information:	Copyright 1983 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Bibliography: l. 159-166. Thesis (M.Sc) - University of Tasmania, 1984
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