Acid-induced denaturation of carp myofibrillar protein.

Denaturation of carp myofibrils induced by changing pH in association with KCl concentration was studied. Myofibrils were mixed with maleate-NaOH buffer to set the pH between 4.98 and 6.21 in the presence of varied concentrations (0.1-1.0M) of KCl and were stored at 2°C. Acid-induced denaturation of myofibrillar protein such as myosin and actin was investigated by means of changes in various ATPase activities and in digestibility by α-chymotrypsin. The results showed that under the acid treatment, the majority of myofibrillar protein was slowly denatured in a complexed form as actomyosin in the presence of low concentration (0.1M) of KCl, whereas through dissociation into myosin and actin in the presence of high concentration (over 0.5M) of KCl. It was also shown that a rise in pH of myofibrils suspension tended to accelerate a preferential denaturation of actin, while a fall in pH caused rapid denaturation of actin together with myosin.