Thesis - Open Access
Doctor of Philosophy (PhD)
Nifungin, an antifungal peptide produced by Aspergillus giganteus, was studied and partially characterized. The amino acid composition of the antifungal peptide was investigated , and eighty-seven percent of the peptide constituents were identified. The presence of free –SH groups in the peptide was studies by spectrophototmetric titration of the peptide with p-hydroroxymercuribenzoate. Performic acid oxidation was used to disrupt the disulfide bridges present in the molecule, and subsequent enzymatic digestion of the oxidized peptide was accomplished with alpha chymotrypsin. Chromatographic separation of the digestion mixture produced eleven chymotryptic peptides. Six of these peptides were selected for amino acid sequence analysis by the Edman degradation method. The results of this study indicated that nifungin is a basic peptide containing a minimum of forty-nine amino acid residues. It contains no tryptophan, histidine or methionine. The peptide has no free –SH groups, but incorporates four disulfine bridges within its structure. The sequence studies on the six chymotryptic peptides showed that these peptides had unusual end-group residues in some instances, based on the specificity of the digesting enzyme, suggesting that the overall nifungin structure was complex.
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South Dakota State University
Cardwell, Burton D., "The Primary Structure of Selected Peptides from Chymotryptic Digests of Nifungin" (1970). Electronic Theses and Dissertations. 5146.