Identification of Cross‐linking Site(s) of Myosin Heavy Chains in Oxidatively Stressed Chicken Myofibrils

ABSTRACT: The cross‐linking site(s) of myosin heavy chains (MHC) in chicken myofibrils exposed to non‐enzymatic, hydroxyl radical‐generation oxidizing systems (HRGS) was investigated by means of chymotryptic digestion and subsequent electrophoresis. Oxidation of the chymotryptic digests resulted in cross‐linking of the rod or light meromyosin (LMM) segment of MHC mostly via disulfide bonds, while subfragment‐1 (S‐1) or heavy meromyosin (HMM) was not affected. A mixture of cross‐linked rod or LMM and uncross‐linked S‐1 or HMM was also produced when myofibrils were 1st oxidized and then digested with chymotrypsin, confirming that cross‐linking of myosin in HRGS‐oxidized myofibrils occurred initially in the LMM portion of the myosin rod.