Factors limiting the hydrolysis of casein by subtilisin DY.

It was shown that during the subtilisin DY-induced hydrolysis of casein relatively stable polypeptide structures are formed. In their interior these structures contain peptide bonds which are susceptible to the enzyme used. Heating (up to 100 degrees C) and/or application of ultrasound (25 kHz, 60 W) results in their unfolding. Data are provided, which show that under the enzyme-substrate complex formation does not lead to an enzyme conformation more susceptible to autolysis. Taking into account the described phenomena a higher degree of hydrolysis was attained in comparison to those obtained by standard enzymatic hydrolysis.