. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 302 LEONARD NELSON reach maximum contraction in the absence of Mg ions, and the enhancing effect of calcium on the ATP-ase activity of these fibers is less than half that of magnesium, the optimum occurring at pH 7 (Sarkar, Szent-Gyorgyi and Varga, 1951). How- ever, at KC1 concentrations high enough to cause dissociation of the actomyosin complex in the presence of ATP, the glycerinated muscle has the same ATP-ase properties as myosin, , alkaline pH optimum and Ca ion activation. Calcium in- INFLUENCE OF ATP CONCENTRATIO
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 302 LEONARD NELSON reach maximum contraction in the absence of Mg ions, and the enhancing effect of calcium on the ATP-ase activity of these fibers is less than half that of magnesium, the optimum occurring at pH 7 (Sarkar, Szent-Gyorgyi and Varga, 1951). How- ever, at KC1 concentrations high enough to cause dissociation of the actomyosin complex in the presence of ATP, the glycerinated muscle has the same ATP-ase properties as myosin, , alkaline pH optimum and Ca ion activation. Calcium in- INFLUENCE OF ATP CONCENTRATION 35. 120 FIGURE 6. Influence of ATP concentration on ATP-ase activity of Mytilus sperm tails. Sperm washed twice in FSW, 4 times in M/2 KC1. Tube contents: M KC1, M veronal buffer pH , 5 X 10~" M MgCL, ATP cone, indicated as y7'-P, 1 ml. sperm tail preparation; total ml. Incubation: 2 hours, 27° C. Aliquots tested at times indicated. Ordinate—yP liberated, abscissa—time in minutes. duces shortening when injected into isolated single muscle fibers (Heilbrunn and Wiercinski, 1947) ; magnesium ions are about 1/70 as potent (Woodward, 1948). Hayashi (1952) has reported that pH is optimum for contraction of pellicu- lar actomyosin fibers, while Kafiani and Engelhardt (1953) noted a shift in the optimum to pH 9 for pellicular myosin fiber contraction, conditions most favorable for the ATP-ase activity of actin-free myosin. It has been pointed out that pro-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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