since enamel proteins become mineralized on secretion , matrix specimens were demineralized in cold 5 % ( w/v ) trichloroacetic acid , extracted with buffered 6m-urea and reduced with mercaptoethanol , and then the solubilized proteins were fractionated by urea/polyacrylamide-gel electrophoresis .
C0011353
enamel proteins
C0033684
proteins