Whitehead, Susan Elizabeth Aannesley (1970)
Studies in the turnover of the bound phosphate of skeletal muscle during contraction and relaxation.
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The possibility that there is a turnover in active muscle of a phosphate fraction which remains attached to the muscle after extraction with aqueous media, was investigated further.A reversible decrease in the specific activity was found when loaded or unloaded frog recti (briefly labelled with-orthophosphate) were contracted by treatment with KCl. Even in the absence of shortening (under isometric conditions or in the absence of calcium ions) a decrease in the specific activity occurred after depolarisation of the membranes.A similar change in specific activity was found when P-labelled glycerol-extracted psoas fibrils were treated with ATP or ITP in the presence of magnesium ions. Ho change occurred when the fibrils were treated with ATP and calcium ions. 2,4-Dinitrophenol did not inhibit the effect of ATP and magnesium ions on the bound phosphate of the myofibrils.In the intact muscle the ATP-p and the P of PC do not become30equally labelled when incubated with P-orthophosphate for 60 min.That material which is extracted as Pi by trichloracetic acid from acetone-dried washed muscle residues has a similar degree of labelling as the ATP-p is isolated from whole muscles.
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in Royal Holloway Research Online.Last modified on 31-Jan-2017
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Institution: University of London, Bedford College (United Kingdom).