Changes in carp myosin ATPase induced by temperature acclimation |
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Authors: | G C Hwang S Watabe K Hashimoto |
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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 |
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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 mol Pi·min-1·mg-1 at 0.2 M KCl for cold-acclimated carp and 0.47 mol 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 mol Pi·min-1·mg-1 at pH 6 and 0.4 mol 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 mol 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 mol 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 5-triphosphatase
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DTNB 5,5
dithio-bis-2-nitrobenzoic acid
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DTT
dithiothreitol
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EGTA
ethyleneglycol bis (-aminoethylether)-N,N,N,N-tetraacetic acid
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K
D
inactivation rate constant
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SDS
sodium dodecyl sulfate
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SDS-PAGE
SDS-polyacrylamide gel electrophoresis |
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Keywords: | Temperature Acclimation Myosin Myosin heavy chain ATPase activity Carp |
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