SynopsisPoly-y-L-glutamic acid has been synthesized by the activated pentachlorophenyl ester polymerization method and the molecule weight of the polymer was found to be 16,000. Comparative conformational studies on the synthetic and on the native polyglutamic acid obtained from B. anthracis and B. subtilis were carried out using optical rotatory dispersion, circular dichroism, peptide absorption spectrum, and titration data. These results show that poly-y-glutamic acid does not exhibit any conformational order under the conditions of investigation. A t low degrees of ionization, restriction of conformational freedom via random "hypercoiling" of the chain appears likely.

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Isolation of a pentaene macrolide antibiotic (NSC-277813) from Streptomyces griseus (FCRC-21) fermentation broth is described. Using field desorption mass spectrometry and high resolution field desorption mass spectrometry on the intact and derivatized antibiotic and degradation products, the antibiotic was identified as fungichromin. The application of field desorption mass spectrometry in the identification of polyene antibiotics is discussed.