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Changes in carp myosin ATPase induced by temperature acclimation
Authors:G C Hwang  S Watabe  K Hashimoto
Institution:(1) Laboratory of Marine Biochemistry, Faculty of Agriculture, University of Tokyo, 113 Bunkyo, Tokyo, Japan;(2) Food Science Laboratory, Faculty of Education, Ibaraki University, 310 Mito, Ibaraki, Japan
Abstract:Summary Myosins were isolated from dorsal ordinary muscles of carp acclimated to 10°C and 30°C for a minimum of 5 weeks and examined for their ATPase activities. Ca2+-ATPase activity was different between myosins from cold-and warm-acclimated carp, especially at KCl concentrations ranging from 0.1 to 0.2 M, when measured at pH 7.0. The highest activity was 0.32 mgrmol Pi·min-1·mg-1 at 0.2 M KCl for cold-acclimated carp and 0.47 mgrmol Pi·min-1·mg-1 at 0.1 M KCl for warm-acclimated fish. The pH-dependency of Ca2+-ATPase activity at 0.5 M KCl for both carp was, however, similar exhibiting two maxima around 0.3 mgrmol Pi·min-1·mg-1 at pH 6 and 0.4 mgrmol Pi·min-1·mg-1 at pH 9. K+(EDTA)-ATPase activity at pH 7.0 neither exhibited differences between both myosins. It increased with increasing KCl concentration showing the highest value of about 0.4 mgrmol Pi·min-1·mg-1 at 0.6–0.7 M KCl. Actin-activated myosin Mg2+-ATPase activity was markedly different between cold-and warm-acclimated carp. The maximum initial velocity was 0.53 mgrmol Pi·min-1·mg-1 myosin at pH 7.0 and 0.05 M KCl for cold-acclimated carp, which was 1.6 times as high as that for warm-acclimated carp. These differences were in good agreement with those obtained with myofibrillar Mg2+-ATPase activity between both carp. No differences were, however, observed in myosin affinity to actin. Differences in myosin properties between cold- and warm-acclimated carp were further evidenced by its thermal stability. The inactivation rate constant of myosin Ca2+-ATPase was 25·10-4·s-1 at 30°C and pH 7.0 for cold-acclimated carp, which was about 4 times as high as that for warm-acclimated carp. Light chain composition did not differ between both carp myosins. The differences in a primary structure of the heavy chain subunit was, however, clearly demonstrated between both myosins by peptide mapping.Abbreviations ATPase adenosine 5prime-triphosphatase - DTNB 5,5prime dithio-bis-2-nitrobenzoic acid - DTT dithiothreitol - EGTA ethyleneglycol bis (beta-aminoethylether)-N,N,Nprime,Nprime-tetraacetic acid - K D inactivation rate constant - SDS sodium dodecyl sulfate - SDS-PAGE SDS-polyacrylamide gel electrophoresis
Keywords:Temperature  Acclimation  Myosin  Myosin heavy chain  ATPase activity  Carp
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