Cross-linking activity of sarcoplasmic fraction from bigeye snapper (Priacanthus tayenus) muscle

Addition of sarcoplasmic fraction from bigeye snapper (Priacanthus tayenus) into natural actomyosin in combination with setting at 40°C resulted in the cross-linking of myosin heavy chain (MHC). Higher amount of sarcoplasmic fraction and extended setting time resulted in a higher cross-linking, indicating the presence of endogenous transglutaminase (TGase) in bigeye snapper muscle. TGase activity was activated by calcium ion and reducing agents (β-mercaptoethanol and dithiotreitol), but was inhibited by N-ethylmaleimide (NEM), NH₄Cl and EDTA. TGase in the sarcoplasmic fraction was not stable when heated at temperature above 40°C, particularly with an increasing heating time. TGase was stable at pH ranging from 5.0 to 7.0, in which more than 70% activity was retained. Therefore, sarcoplasmic fraction possessed a cross-linking activity caused by TGase and its recovery for further uses should be considered.