Identification of the glutamine residue that may be involved in the transglutaminase-mediated intramolecular crosslinking of carp and walleye pollack myosin

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In order to elucidate the molecular mechanism of transglutaminase-mediated myosin cross-linking, a fluorescent monodansylcadaverine (MDC) was incorporated into carp Cyprinus carpio myosin and the reactive Gln residues were analyzed by cyanogen bromide cleavage. The fluorescence was predominantly detected in a 10.5 kDa BrCN-fragment, which is assumed to be located in subfragment 2 of the myosin heavy chain. Furthermore, lysyl endopeptidase digestion of the 10.5 kDa fragment revealed that MDC was specifically incorporated into the 520th Gln residue of the subfragment 2 domain. When meat paste prepared from walleye pollack Theragra chalcogramma frozen surimi was incubated with MDC, the fluorescence was mostly observed in a 16 kDa BrCN-fragment and also slightly detected in other three bands. By the digestion of 16 kDa fragment with lysyl endopeptidase, it was elucidated that MDC was incorporated specifically into Gln-520 of myosin subfragment 2, as well as detected in carp. This domain around Gln-520 is likely to be a common critical region for dimer formation of myosin heavy chains for both fish species. In walleye pollack, other reactive Gln residues are presumed to be exist in the C-terminus of the light meromyosin. This slight difference may be significant in a capacity to form tetramers or even larger multimers.
2009-11-01