When carp myosin B was incubated at 25°C, SDS-PAGE showed that an addition of a soluble extract from Alaska pollack muscle and surimi greatly stimulated the cross-linking reac-tion of myosin heavy chains. This effect was completely lost on boiling but not with dialysis, suggesting the presence of an active enzyme, transglutaminase, in the extract. It was, therefore, purified from Alaska pollack muscle by DEAE-cellulose chromatography and Sephadex G-200 gel filtration.
The partially purified enzyme catalyzed the cross-linking reaction of myosin heavy chain and also showed an activity to incorporate a fluorescent amine, monodansylcadaverine, into acety-lated casein. SDS-PAGE analysis of carp myosin B incubated with the enzyme in the presence of monodansylcadaverine showed several fluorescent bands, including myosin heavy chain and its polymers, with a depletion of fluorescence on actin, tropomyosin and connectin bands. The transglutaminase activity was found at a molecular weight of about 85, 000 by the gel filtration and required Ca2+.
From these results, the presence of transglutaminase was ascertained in Alaska pollack muscle and surimi. The setting of the salted paste of muscle or surimi may thus involve at least the enzymatic process in gel network formation.
