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1992 (1)
1980 (1)
1Author    ErwinW. BeckerRequires cookie*
 Title    Dynamics and Kinetics of Enzymes Kinetic Equilibrium of Forces in Biochemistry  
 Abstract    To explain the high specificity, high reaction rate, and high thermodynamic efficiency in enzymatic processes, cooperation of the enzyme with a molecular transfer unit is assumed. A "kinetic equilibrium of forces" is suggested, which enables high reaction rates to occur under equilibrium conditions and a thorough examination of the substrate to be made without con­ sumption of free energy. In case o f ATPases, ion-binding proteins are the most probable trans­ fer units. By analyzing the elementary effect in muscle contraction it is shown that the new theorem may be of substantial value in elucidating biochemical processes. 
  Reference    Z. Naturforsch. 47c, 628—633 (1992); received May 18 1992 
  Published    1992 
  Keywords    Enzyme, Mechanism, Free Energy Transfer, ATPase, Calmodulin, Muscle Contraction 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0628.pdf 
 Identifier    ZNC-1992-47c-0628 
 Volume    47 
2Author    Peter DanckerRequires cookie*
 Title    Tropomyosin-Troponin-Induced Changes in the Partitioning of Free Energy Release of Actomyosin-Catalyzed ATP Hydrolysis as Measured by ATP-Phosphate Exchange  
 Abstract    ATPase activity and ATP-Pj exchange o f unregulated (without tropomyosin-troponin) and regulated (with tropomyosin-troponin) acto-HMM were measured in media containing 0.2 mg/ml actin, HMM, and (when present) tropomyosin-troponin, 2 m M MgCl2, 10 m M KC1, 2 m M N aN 3, 10 m M Pi (pH 7.0), 3 mM ATP. The following mean values for ATPase activity and for the rate o f incorporation of P, into ATP (each per mg HMM and per min) were obtained: unregulated acto-HMM 0.33 |imol Pj and 0.33 nmol Pi? regulated acto-HMM 0.54 nmol Pi and 1.06 nmol P*. The ratio o f P4 incorporation rate to ATPase activity was 1.01 x 10-3 for unregulated and 2.02 x 10-3 for regulated acto-HMM. From these ratios and from the overall free energy change o f ATP hydrolysis it was calculated that under the prevailing experimental conditions in unregulated acto-HMM 62% and in regulated acto-HMM 66% o f the free energy change o f ATP hydrolysis occurs after the release o f phosphate from actomyosin. It is probably this part of the free energy change that is used by the muscle for the performance o f work. 
  Reference    Z. Naturforsch. 35c, 431—438 (1980); received November 19 1979/January 15 1980 
  Published    1980 
  Keywords    Actomyosin ATPase, ATP-Phosphate Exchange, Energy Transduction, Tropomyosin-Troponin, Muscle Contraction 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0431.pdf 
 Identifier    ZNC-1980-35c-0431 
 Volume    35