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1980 (1)
1Author    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