Glutamic Acid of Proteins

THE recent claim of Kögl and Erxleben1 that the proteins of malignant tissues are partially race-mized was based largely on the observation that the hydrolysates of such proteins, unlike those derived from normal tissues, contained glutamic acid which showed evidence of racemization, in some cases to a high degree. In our preliminary communication2 we directed attention to the fact that we had been able to isolate the normal, unracemized, I (+) glutamic acid hydrochloride in good yield from three different samples of malignant tissue protein material, and suggested that a more extensive investigation was needed before Kögl and Erxleben's claim could be admitted. In reply, these latter workers3, inter alia, produced evidence which they believed to show that our modified Foreman4 method of analysis was unsuitable for demonstrating the presence of any racemized glutamic acid in protein hydroly sates, because the calcium salt of this acid is more soluble in 90 per cent alcohol than is that of the natural I (+) antipode, and also because the racemic hydrochloride is more soluble in either concentrated or 20 per cent hydrochloric acid than is that of the natural product.