Procedure for Electrophoretic Separation and Visualization of Milk-Clotting Enzymes in Milk Coagulants

Abstract

A polyacrylamide gel electrophoresis system has been developed for separating commercial milk coagulants and mix~res of coagulants. The electrophoretie patterns of the samples are made visual by layering milk over the fiat polyacrylamide gel slab. Areas having milk coagulating activities exhibited zones of dotted milk, which are easily seen. Standard calf rennet separated into two components which migrated toward the anode: a slow moving major band (rennin) and a faster moving minor band (calf pepsin). Rennet from older calf stomachs has a bovine pepsin component whose electrophoretic mobility is slightly faster than that of calf pepsin. Porcine pepsin migrated as a single component at mobility slightly faster than that of bovine pepsin. Microbial rennins exhibited varying migration patterns under these conditions. The systern is sensitive enough to separate and to make visible as little as 5~; of a coagulant mixed with another coagulant having a different migration rate.