A STUDY OF THE EQUILIBRIUM BETWEEN THE SO CALLED "ANTITRYPSIN" OF THE BLOOD AND TRYPSIN. BY RAYMOND G. IilISSEY AND JOHN

I t has been a well known fact for some time that blood serum has the property of retarding the digestive activity of trypsin. We have, however, no satisfactory information regarding either the nature of the substance which effects the retardation or the type of chemical reaction involved in the process. At one time the inhibitory agent was thought to be an immune antibody and in accordance with custom it was called antitrypsin. There is no evidence to support the idea that the active agent is of the nature of an immune body, so the term antitrypsin is incorrect. Landsteiner (1) found that the retarding effect was associated with the albumin fraction of serum. Hedin (2, 3) then employed preparations of serum albumin as "antitrypsin" in one of the few experimental inquiries that have been made with the view of studying the nature of the trypsin-antitrypsin reaction (4). While these studies were in progress, Hedin 1 (5) discovered that charcoal adsorbed trypsin and that the equilibrium between these two substances satisfied the conditions demanded by the equation representing adsorption phenomena. A comparison of the experimental results obtained when retardation was effected by charcoal with those of the experiments when serum albumin was used presented so many similarities that Hedin was led to the conclusion that the equilibrium between trypsin and "anfitrypsin" ~serum albumin) was also governed by adsorption phenomena; that is, the trypsin was adsorbed by the serum albumin as it was by the charcoal. I t was, however, not possible to obtain values from the experiments to substitute in the adsorption equation. They seemed plausible, though, because