Degradation of Casein Components by Acid Protease of Bovine Milk

Degradation of ~sl', 3-, and K-caseins by an acid protease of bovine milk was studied by disc and urea-sodium dodecylsulfate electrophoresis. The acid protease converted ~sl-casein into a fragment, with a mobility equal in both disc and urea-sodium dodecylsulfate electrophoresis to that of % z-I casein produced by the action of chymosin. New bands, with mobilities equal in disc and ureasodium dodecylsulfate electrophoresis to those of /3-I and/3-II fractions produced by chymosin action, appeared by the action of acid protease on /3-casein. Furthermore, a para-K-casein-like protein was formed from ~-casein by the acid protease. However, the para--casein-like protein was formed much slower by the acid protease than was para-K-casein by chymosin.