Effect of aspartyl proteinases ofPenicillium caseicolumandPenicillium roquefortion caseins

Abstract
SUMMARY: The aspartyl proteinases ofPenicillium caseicolumandP. roquefortiacted identically on β-casein; both enzymes split at least 3 bonds: Lys29–Ile30, Lys97–Val98and Lys99–Glu100. From αsl-casein, these proteinases released 6 main degradation products which arose from the splitting of 4 bonds;P. roquefortiaspartyl proteinase was found to cleave 1 bond at a higher rate thanP. caseicolumaspartyl proteinase. A hypothetical sequential hydrolysis mechanism of αsl-casein by these 2 enzymes is proposed from a study of the degradation by isoelectric focusing and by 2-dimensional electrophoresis.