THE MECHANISM OF OVALBUMIN PROTEOLYSIS

Papain, thermitase, and pepsin at pH 4.0 hydrolyze ovalbumin to low molecular weight peptides. During hydrolysis several short fragments form in succession with the appearance of a group of high molecular weight fragments, the latter subsequently splitting into fragments of intermediate molecular mass. The fragments are retained in the molecule by noncovalent bonds. The fragments formed during catalysis by different enzymes are similar in size, suggesting that the splitting occurs in the same short segments of the ovalbumin polypeptide chain. The results indicate that during proteolysis of native ovalbumin the two extreme types of proteolysis (random and limited) occur in parallel, the course of the latter being determined by the ovalbumin structure.