Influence of exercise on the distribution of enzymes in trout white muscle and kinetic properties of AMP-deaminase from free and bound fractions |
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Authors: | V I Lushchak K B Storey |
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Institution: | (1) Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario, Canada, KIS 5B6;(2) Present address: Karadag Branch of Southern Seas Biology Institute, Academy of Sciences of Ukraine, p/s Kurortne, Feodosia, Crimea, 334876, Ukraine |
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Abstract: | Effects of exercise on the distribution of phosphofructokinase (PFK), fructose-1,6-biphosphatase (FBPase), and AMP-deaminase
between free and particulate-bound fractions was analyzed in white skeletal muscle of rainbow trout Oncorhynchus mykiss. With a widely used technique for the separation of free and bound enzyme fractions (homogenization in low ionic strength,
high sucrose buffer), the data showed that the amount of bound PFK increased from 64 to 95% during burst swimming whereas
other enzymes were unaffected. Since this data for AMP-deaminase contrasted with earlier reports, different methods of separating
free and bound enzyme were evaluated. A clear effect of exercise on AMP-deaminase binding occurred when high ionic strength
media (either KCl or KF) were used; in extraction media containing 150 mM KCl, the percent bound rose from 30% in controls
to 97% after 1 min burst swimming. Exercise also produced stable changes to AMP-deaminase kinetic properties, including for
the bound enzyme (compared with the free) a 2-fold higher Km AMP, a 3-fold higher Ki for inorganic phosphate, and a 60% increase in Ka ADP after 1 min burst exercise. The data suggest that AMP-deaminase in working skeletal muscle is subject to combined controls
by allosteric effectors, post-translational modification, and distribution between free and bound states. |
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Keywords: | Oncorhynchus mykiss phosphofructokinase fructose- 1 6-bisphosphatase enzyme binding exercise AMP-deaminase regulatory properties |
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