Abstract
In a previous paper, we have reported that the hydrolysis rate of casein by alkali protease is much enhanced by the presence of oxidizing agent. The present paper describes detailed studies of such an enhancement by sodium perborate, sodium percarbonate and hydrogen peroxide in the hydrolysis of casein and its components, α-, β- and κ-casein by two kinds of alkali proteases. The hydrolysis has been followed up with the modified casein-folin method and gel permeation chromatography (GPC).
The results can be summarized as follows.
(1) The oxidizing agents do not reduce the enzyme activities.
(2) The order of the contact of the three components is important for the enhancement; in case that casein comes in contact first with oxidizing agent and then with enzyme, the hydrolysis rate is most enhanced by ca. 60%.
(3) Such an enhancement was found for the casein components, α-, β- and κ-casein, respectively.
(4) Data of GPC showed that casein is degraded by oxidizing agent to fragments with ca. 103 dalton, which are hydrolyzed to smaller fragments by the enzyme, faster than casein itself.
