The Effect of Alkali Treatment Upon Acetyl Proteins

Landsteiner (1) acetylated the proteins of horse serum by means of acetic anhydride.The acetyl proteins which he prepared contained from 4.75 to 10.86 per cent of acetyl groups.Some of these preparations were made by heating the protein with acetic anhydride on a water bath for varying lengths of time.Others were made by allowing the acetic anhydride to react with the protein at room temperature.The acetyl proteins which were prepared at room temperature contained less acetyl than those prepared by heating.Other workers, for example, Troensgaard and Mygind (2), have prepared acetyl derivatives of protein, but they used acetyl chloride dissolved in glacial acetic acid.They must have obtained disintegration products by this method, for Fodor and Epstein (3) have shown that even acetic anhydride may cause decomposition of gelatin when a mixture of the two is kept at the temperature of boiling acetic anhydride for an hour.This, doubtless, explained why Landsteiner found a higher per cent of acetyl in those acetyl proteins which were prepared by aid of heat.Herriott and Northrop (4) and Herriott (5) have acetylated pepsin by means of the ketene reaction in such a way that there was obviously no destruction of the protein, for some of the peptic activity of the protein was retained by the acetyl pepsin and much of it could be restored by the hydrolytic removal of some of the * A preliminary report of this work was made before the meeting of the