Inhibition of myosin B-adenosinetriphosphatase by excess substrate

Tonomura, Yūji; Yoshimura, Junko

doi:10.1016/0003-9861(60)90614-7

Cited by 49 publications

(18 citation statements)

References 22 publications

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“…the regulated step; Sleep et al, 1981), but not the ability of S1-ADP to bind to regulated actin in a cooperative m a n n e r that was somewhat influenced by calcium (Greene & Eisenberg, 1980), it was of interest to investigate the effect of this modification on the calcium regulation of the in vitro actinactivated myosin Mg2+-ATPase. Tonomura and Yoshimura (1960) observed that incubation of myosin B (which consists of myosin, actin, troponin and tropomyosin) with PCMB resulted in a loss in the calcium sensitivity of superprecipitation. Subsequent experiments by Staprans et al (1968) and Ebashi et al (1968) *100% activities (average n = 7) in p, mol/min-lmg 1: K+_ATPase = 1.42; Ca2+-ATPase = 0.123; -C a 2+ Mg2+-ATPase = 0.038; + C a 2+ Mg2+-ATPase = 0.738. tThe actomyosin ATPase activity was measured in these cases (i.e.…”

Section: Discussionmentioning

confidence: 98%

SH-1 modification of rabbit myosin interferes with calcium regulation

Titus¹,

Ashiba²,

Szent‐Györgyi³

1989

J Muscle Res Cell Motil

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The reactive thiol of the myosin head, SH-1, can be selectively labelled in glycerinated rabbit muscle fibres. This residue has been used as an attachment site for either fluorescent or spectroscopic probes which report on head movements and orientations in various functional states of muscle. We have specifically modified SH-1 in vitro, using purified rabbit myosin and conditions similar to those employed in the labelling of muscle fibres (low ionic strength [40 mM NaCl] at 4 degrees C), with stoichiometric amounts of either [14C]-iodoacetamide, 5-(2[iodoacetyl)amino)ethyl) aminonaphthalene-1- sulphonic acid (IAEDANS), or 4-(2-iodoacetamido-2,2,6,6-tetramethyl piperidinooxyl (IASL). The specificity of modification was determined by measuring the well-defined alterations in the high salt ATPase activities of myosin and by localizing both IAAm and IAEDANS to the 20-kDa C-terminal subfragment 1 (S1) which contains SH-1. The low ionic strength actin-activated Mg2+-ATPase of SH-1-modified rabbit myosin was measured in the presence of the thin filament regulatory, complex, troponin-tropomyosin. A significant increase in this activity in the absence of calcium, concomitant with a decrease in activity in the presence of calcium, was observed as the extent of SH-1 modification was incrementally increased from zero to one mole of label bound per mole of SH-1. The elevated myosin Mg2+-ATPase, which results from SH-1 modification, does not account for the increased actin-activated Mg2+-ATPase in resting conditions (i.e. in the absence of calcium).(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussionmentioning

confidence: 98%

SH-1 modification of rabbit myosin interferes with calcium regulation

Titus¹,

Ashiba²,

Szent‐Györgyi³

1989

J Muscle Res Cell Motil

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“…When the Ca2+ concentration is kept as low as possible the rate of hydrolysis of ATP is greater at very low concentrations of ATP (ca. 10-5 M) than at physiological concentrations of 1-10 mm (Tonomura & Yoshimura, 1960;Chaplain, 1966;Weber, 1969 (1963) concluded from their work that calcium was not necessary for superprecipitation provided the ATP concentration was sufficiently low, and Levy & Ryan (1965) showed that with ATP below 10-5 M, calcium even inhibited superprecipitation. Maruyama & Gergely (1962a, b) demonstrated that when superprecipitation occurred in the absence of calcium there was a momentary increase in the rate of ATP hydrolysis.…”

Section: Discussionmentioning

confidence: 99%

Rigor contraction and the effect of various phosphate compounds on glycerinated insect flight and vertebrate muscle

White¹

1970

The Journal of Physiology

106

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SUMMARY1. Glycerol-extracted flight muscle from the giant water-bug, Lethocerus cordofanu8, undergoes contraction when deprived of ATP. This rigor contraction occurs in the presence of the calcium chelating agent EGTA, under conditions in which the predicted free calcium ion concentration is less than 5 x 10-9 M. A mechanically similar contraction has been observed by depriving the muscle of Mg2+, in the presence of 5 mM-ATP.2. In the rigor contraction tensions ofup to 120 mN/mm2 under isometric conditions, and shortenings of between 2 and 6 % under isotonic conditions, have been observed at 20°C.3. Muscles in rigor can be relaxed by the addition of ATP. The minimum concentration of ATP required to give full relaxation depends upon other ionic constituents of the solutions, and upon temperature, but is between 0-3 and 1 mm at 200 C. Lower concentrations result in partial reduction of tension and stiffness.4. Pyrophosphate (PP) causes a reduction in the tension of muscle which has developed rigor under isometric conditions, but the stiffness, when measured at frequencies between 1 and 100 Hz, remains indistinguishable from that of rigor muscle. The stiffness when measured by applying slow length changes is comparable to that of ATP-relaxed muscle. It is suggested that in PP-relaxed muscle the cross-bridges remain in close proximity to, but are not rigidly attached to, the I filaments, resulting in a high viscous interaction between the two sets of filaments.5. The addition of low concentrations of ADP (less than about 0 7 mM) to rigor muscle in the absence of ATP causes an increase in tension. The effect is sigmoid, and is probably due to the formation of low concentrations of ATP throughout the body of the fibre by myokinase activity. Larger concentrations of ADP (about 5 mM) added to rigor muscle cause relaxation, probably due to the formation of higher ATP concentrations.6. AMP and inorganic orthophosphate have little effect upon the mechanical properties of rigor muscle.7. There is a delay of about 1 min before the onset of rigor contraction when fibres are transferred from an ATP-solution to one containing no ATP, due to the transfer of ATP in the body of the fibres. Both ATP hydrolysis by the fibres and diffusion of ATP into the bathing solution contribute significantly to the rate of depletion of ATP.8. Rabbit psoas muscle shows a similar rigor contraction in the presence of EGTA, and has mechanical properties similar to those described for Lethocerus flight muscle in the presence of pyrophosphate.

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“…Interaction with actin, however, transforms the Mg^^-inhibited enzyme into a Mg^^-activated enzyme (Banga and Szent-2+ Gyorgyi, 1943). This Mg -activation is observed with actomyosin at low ionic strengths, but at ionic strengths of 0.2 or above, addition of ATP leads to dissociation of the actin-myosin complex, and the enzy matic characteristics of myosin ATPase reappear (Hasselbach, 1956;Tonomura and Yoshimura, 1960;Leadbeater and Perry, 1963). In addition…”

Section: +mentioning

confidence: 86%

Localization of [alpha]-actinin and tropomyosin in muscle and nonmuscle systems

Schollmeyer¹

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Inhibition of myosin B-adenosinetriphosphatase by excess substrate

Cited by 49 publications

References 22 publications

SH-1 modification of rabbit myosin interferes with calcium regulation

SH-1 modification of rabbit myosin interferes with calcium regulation

Rigor contraction and the effect of various phosphate compounds on glycerinated insect flight and vertebrate muscle

Localization of [alpha]-actinin and tropomyosin in muscle and nonmuscle systems

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