The Enzymatic Synthesis of Protein. I

-4 condition in which a synthesis of protein-like material occurs, was first arranged in 1886 by Danilewski (1) who observed the formation of a precipitate when stomach extract was added to a concentrated solution of the products of peptic hydrolysis. He considered the causative agent to be an enzyme, because precipitation did not occur if the stomach extract had been previously heated to 100°C. This result was confirmed in 1895 by Okunew. Both Danilewski and Okunew concluded that the reaction involved synthesis of the products of protein decomposition into a more composite molecule approaching in complexity a native protein. In 1901 Sawjalow (2, 3) investigated the phenomenon more extensively and named it plastein formation. He recognized the necessity for a suitable degree of acidity though he did not define it precisely. Using Witte’s peptone in a concentration of 27.2 per cent, Sawjalow obtained 13.6 per cent of the total dry weight in the precipitate. He attempted an estimation of the molecular weight of plastein by means of acid and alkali titration and arrived at an average value of 6,087. Sawjalow and other workers, Lawrow and Salaskin (4), Kurajeff (5), and Bayer (6) sought to discover the source of plastein among the various fractions obtained by the method of Pick from a protein digest, but failed to reach any agreement. Bayer reached the conclusion that proteoses took no part in the synthesis of plastein. rl. E. Taylor (7, 8) and T. B. Robertson (9, 10) have reported synthesis of protein by means of trypsin and pepsin. In Taylor’s experiments the synthesis was accomplished after 5 months standing and the yield was very small. In Robertson’s experiments the yield was larger and more rapidly obtained. Robertson found indications which led him to assume the existence in pepsin of separate hydrolyzing and synthesizing components. Our experiments indicate that this assumption was possibly erroneous.