Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.4.1 (myosin ATPase)
 1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of Cd2+ on Ca2+-sensitive myosin ATPase activity were examined. In the absence of Ca2+, the Ca2+-dependent myosin ATPase activity was enhanced by Cd2+ to the same extent as with Ca2+ at concentrations ranging from 10(-6) to 10(-3) M. At 10(-2) M, however, no activation was observed. Zn2+, Co2+, and Sr2+ also activated the myosin ATPase. Sr2+ and Co2+ were less effective. Hg2+, Cr3+, and Cu2+ were essentially inactive. In the presence of below 10(-3) M Ca2+, the increase in the enzyme activity observed on the addition of Cd2+ was in addition to that caused by Ca2+ alone. The ability of metal ions to activate myosin ATPase was compared with that to activate calmodulin-dependent cAMP phosphodiesterase. The activating effects of the metal ions tested were in the order of Ca2+ greater than Cd2+ greater than Zn2+ greater than Co2+ greater than Sr2+ for Ca2+-sensitive myosin ATPase and Ca2+ greater than Cd2+ greater than Sr2+ greater than Zn2+ greater than Hg2+ greater than Co2+ for cAMP phosphodiesterase. Cd2+ activated both enzyme activities most efficiently among the metal ions tested except Ca2+. These results indicate that Cd2+ is able to substitute for Ca2+ in the case of Ca2+ dependent enzymes, regardless of whether or not calmodulin participates in the activating process.
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PMID:Enhancement of Ca2+-sensitive myosin ATPase activity by cadmium. 282 3

2'(3')-O-[N- [2- [3- [5-fluoresceinyl] thioureido] ethyl] carbamoyl] adenosine 5'-triphosphate (FEDA-ATP), a spectroscopic tool used for studying skeletal muscle myosin ATPase subfragment 1, was applied to Na+/K+-ATPase (EC 3.6.1.37). In contrast to the myosin subfragment, we found that FEDA-ATP is not a substrate for Na+/K+-ATPase. On the other hand, FEDA-ATP showed an affinity for both the low (E2, Kd=200 microM) and the high (E1, Kd=22 microM) affinity ATP-binding sites. When the microscopic affinities of FEDA-ATP were used for calculating the macroscopic affinity in the overall reaction according to Ki=(KdE1*KdE2)1/2, the experimentally measured inhibition constant of 66 microM was obtained. To evoke irreversible binding inhibitors, FEDA-ATP was transferred in its chromium(III) and cobalt(III) complex analogs, which are suitable tools for labelling the ATP binding sites of Na+/K+-ATPase in a specific way.
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PMID:2'(3')-O-[N- [2- [3- [5-fluoresceinyl] thioureido] ethyl] carbamoyl] adenosine 5'-triphosphate and its Cr(H2O)4 and Co(NH3)4 complex derivatives are new fluorescent tools for labelling ATP binding sites of Na+/K+-ATPase. 972 79