title: 2,4-Dinitrophenol as a specific inhibitor of the breakdown of the actomyosin-phosphate-ADP complex.
abstract: 2,4-Dinitrophenol (DNP) was found to cause a "clearing response" of myosin B in a medium in which "superprecipitation" of myosin B would otherwise take place. The effect of actin concentration on Mg-ATPase [EC 3.6.1.3] of HMM was studied in the presence and absence of DNP. The results indicate that DNP causes an increase rather than a decrease in the affinity of HMM for actin, and that it causes a decrease only in the actin-activated portion of the Mg-ATPase activity. Using a light-scattering technique, it was shown that neither the ATP-induced dissociation of acto-HMM nor subsequent reassociation is significantly affected by the presence of DNP. As for the formation of the myosin-phosphate-ADP complex in the myosin-ATPase reaction, it was shown that formation of the reactive complex is not affected by DNP. It can thus be concluded that DNP inhibits the decomposition of the actomyosin-phosphate-ADP complex, which is thought to be coupled with superprecipitation.
mesh_terms: D000199:Actins / Q000494:pharmacology; D000205:Actomyosin / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004140:Dinitrophenols / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009132:Muscles / Q000378:metabolism; D015879:Myosin Subfragments / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D011817:Rabbits
chemical_list: D000199:Actins; D004140:Dinitrophenols; D015879:Myosin Subfragments; D000255:Adenosine Triphosphate; D000205:Actomyosin; D000251:Adenosine Triphosphatases; D009218:Myosins; D008274:Magnesium