Structure and Enzymatic Break-Down of Proteins

Since the beginning of quantitative r search in the field of protein chemistry much weight has been laid upon investigations attempting to prove that proteins are attacked by the same enzymes that are able to split peptide bonds in the simpler com-pounds. Numerous more or less reliable demonstra-tions of this fact have been regarded as valuable vi-dence that proteins have a peptide chain structure. On various occasions (LinderstrCm-Lang, 1933, 1939a, b) the author has issued warnings against a too optimistic opinion about his line of argumenta-tion, the main points being: 1. The difficulty of establishing the homogeneity of an enzyme ven when isolated as a crystalline pro-tein.