On the relationship between the urea-soluble and citric acid-soluble proteins of bovine snout epidermis.

Abstract

This report presents evidence that the urea‐extractable proteins and the citric acid‐extractable protein (‘prekertin’) of bovine snout epidermis are related. Prekeratin was solubilized by trypsinization, S‐carboxymethylation, 6 mol/l urea or 0·05 mol/l NaOH. trypsinization or S‐carboxymethylation produced at least two species of soluble proteins. 6 mol/l urea at 37°C solubilized prekeratin, but a homogeneous product was not obtained. Depending upon the duration of exposure, prekeratin was cleaved by 0.05 mol/l NaOH at 25°C to form several soluble derivatives, whereas at comparable time intervals at 4°C both insoluble and soluble derivatives were produced. The various soluble proteins derived from prekeratin showed precipitin bands of identity with the urea‐extracted proteins of beef snout epidermis when reacted in agar with antisera raised against the urea‐extracted protein which precipitated at pH 6.3 and 5.5. It is suggested 6 mol/l urea and 0.05 mol/l NaOH may cleave prekeratin in situ to release the proteins extracted by urea and alkali respectively.