The pressure, temperature and ion relations of myosin atp‐ase

Abstract

The kinetics of the hydrolysis of adenosine triphosphate (ATP) by the muscle protein myosin have received considerable attention in recent years, and several reviews have been devoted to this subject (Szent-Gyiirgyi, '55; Morales et al., '55; Buchthal et al., '56). The BTP-ase activity of myosin is modified by pressure (Laidler and Beardell, '55)' by calcium, magnesium and nucleotides (Blum, '55), and by calcium, pH and temperature (Green and Mommaerts, '54; Ouellet et al., '52). The effects of pressure, temperature and ions on ATP-ase activity have been interpreted in terms of a simple Michaelis-Menten reaction scheme (Laidler and Beardell, '55 ; Green and Mommaerts, '54)' although other studies of the behavior of myosin have implicated a series of reactions (Mommaerts and Hanson, '56; Morales et al., '55; Watanabe et al., '53). I n fact, Spicer ('55) has suggested that reversible denaturations may explain gelation phenomena in solutions of myosin B. Our interest in the problem arose from the observation that pressure reduces the isometric twitch tension of intact muscle at lower temperatures and increases it at higher (Cattell and Edwards, '28). This has been ascribed to the effect of presl This investigation was aided by grants from the Dazian Foundation for Medical Research,

The temperature dependence of myosin-adenosinetriphosphatase and alkaline phosphatase in lizards

“…9000 cal/mole. This latter value is very similar to that reported for precipitated myosin from rabbit psoas muscle at comparable temperatures (Brown et al, 1958).…”

An inverted seated posture decreases elbow flexion force and muscle activation

“…Early investigations into the effects of high pressure on animal muscle were conducted by Cattell and Edwards (1928) and Brown (1934) who found that high pressure applied to the muscle at the onset of contraction increased the twitch tension (Cattell and Edwards 1928) while decreased rates of contraction and relaxation (Brown 1934). Both Brown et al (1958) and Ikkai and Ooi (1969) found that raised muscle hydrostatic pressure decreased the attraction of actin to myosin, thereby hindering the actomyosin ATPase reaction. Geeves and Ranatunga (1987) reported a 15% decrease in isometric active tension in a maximally calcium activated rabbit psoas muscle fiber under high hydrostatic pressures.…”

Hydrostatic pressure effects on rabbit and echinoderm myosin ATPase

“…The effect changes on substitution of Verona1 for Tris buffer or on addition of millimolar concentrations of calcium salts. This finding is shown to reconcile the varied reports of pressure effects on myosin ATPases found in the literature (1,5,6). Although pressure also favors polymerization of myosin (7) and alters several properties of fresh and glycerinated muscle (reviewed by Brown (S)), it is premature to relate these effects to the enzymes.…”