CONTROL OF THE DEGREE OF HYDROLYSIS OF A PROTEIN MODIFICATION WITH IMMOBILIZED PROTEASE BY THE PH-DROP METHOD

A mathematical model, DH = 1/k(10(-2DELTApH) - 1), between the pH-drop (DELTApH) and degree of hydrolysis (DH) of an enzymatic modification of casein was developed to assess the DH in a packed-bed column reacto r by directly monitoring the pH value of the modified protein system. It was demonstrated that the linear DH range and the k value of the eq uation were dependent on the reactor type and the specificity of the p roteolytic enzymes immobilized on chitin used in the present study, bu t no effect of the substrate casein concentration on the linear DH ran ge was observed. Since DH and DELTApH values of the modified casein co rrelated with the flow rate in a packed-bed column reactor, it was sug gested that the DH value, in a considerably wide range of casein modif ication with a certain immobilized protease in a column reactor, could be controlled by adjusting the flow rate of the substrate and monitor ed by a pH-meter. This relationship might be used as a basis for scale -up and long-term operation of enzymatic modification of proteins by i mmobilized protease in a column reactor.