Alkali-induced Denaturation of Carp Myofibrillar Protein.

Denaturation of carp myofibrils induced by changing pH in association with KCl con-centration was studied. Myofibrils were mixed with glycine-NaOH buffer to set the pH between 9.73 and 11.04 in the presence of varied concentrations (0.1 ?? 1.0M) of KCl and stored at 2°C. Alkali-induced denaturation of myofibrillar protein such as myosin and actin was investigated by means of changes in various ATPase activities and in the digestibility by α-chymotrypsin. The results showed that under the alkali treatment, the majority of myofibrillar protein was slowly denatured in a complexed form as actomyosin in the presence of a low concentration (0.1M) of KCl, whereas it was rapidly denatured through dissociation into myosin and actin in the presence of a high concentration (over 0.5M) of KCl. It was also shown that under the alkali pH, a fall in pH of myofibrils suspension brought about slow denaturation of actin together with myosin, while a rise in pH caused rapid denaturation of both actin and myosin.