Dilatometric Ultra-Micro-Estimation of Peptidase Activity

Abstract

As appears from recent publications of Indian workers (Sreenivasaya and Bhagvat¹, compare also Rona and Fischgold²), a considerable volume change is observed in systems in which enzymatic cleavages take place. This volume change may be applied to the estimation of enzyme activity, and the dilatometric methods thus developed possess certain advantages, among which may be mentioned the continuous observation of the undisturbed enzymatic process. While looking around for possible means of refining the histochemical methods previously de-scribed (Linderstrøm-Lang and Holter³), I came across the falling drop method for the measurement of specific gravity (Barbour and Hamilton⁴), a method which recently was re-investigated and improved by Fenger-Eriksen, Krogh and Ussing⁵. Experience with this method led to the development of a static principle of measurement especially suited for estimation of volume changes in small drops and therefore for micro-estimation of enzyme activity. The following description is concerned only with the application of the method for this latter purpose, but the method may prove useful for the estimation of specific gravity also in other cases.