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)

L(+)Lactic acid enhances myosin ATPase in vitro. Different organic acids were tested for activation of myosin ATPase activity. L(+)Lactic is more effective in stimulating ATPase than D(-)Lactic. D(+) and L(-)Malic acids were also effective at the concentration of 2.5 x 10(-2)-5.0 x 10(-2) mmoles/l. At 3.0 x 10(-2) mmoles/l concentration the following acids are activators: acetic, oxalic, malonic, oxaloacetic, pyruvic, glyoxylic, glycolic; succinic is an inhibitor and acetoacetic is without effect. The activation is not in relation with the pKa of these acids. The inhibitory effects of organic acids are evident at the concentration of 5.0 x 10(-2) mmoles/l. This inhibitory effect is linearly increasing with their pKa. The results are discussed in connection with the possible role of these metabolites in controlling not only ATPase activity towards splitting of ATP, but also in controlling the removal of its hydrolytic products.
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PMID:Effects of monocarboxylic and dicarboxylic acids on myosin ATPase activity tested by luminometric procedure. 153 14

1. Cross sections from the middle of the gluteus medius were removed from 10 adult horses and used to evaluate changes in histochemically determined muscle fiber type and biochemically determined metabolic enzyme activities as a function of sample depth. 2. Muscle fiber types determined using histochemical methods for myosin ATPase (pH 9.4) and succinic dehydrogenase (SDH) activity indicated percent fast-twitch glycolytic (FG) muscle fibers decreased and slow-twitch oxidative (SO) fibers increased as a function of increasing sampling depth. 3. Percent histochemically determined fast-twitch oxidative glycolytic (FOG) fibers decreased slightly only in the deepest region of the gluteus medius. 4. Citrate synthase (CS) enzymatic activity, used as a marker for mitochondrial oxidative potential, increased 2.5-fold in activity per g of muscle protein from 1 to 8 cm sampling depth. 5. 3-hydroxyacyl-CoA dehydrogenase (HAD) enzymatic activity, used as a marker for lipid oxidation potential, increased 3-fold in activity per g of muscle protein when the depth increased from 1 to 8 cm. 6. Phosphorylase (PS) enzymatic activity, used as a marker for potential glycogen utilization, decreased 50% in activity per g of muscle protein when going from 1 to 8 cm. 7. Lactate dehydrogenase (LDH) enzymatic activity, used as a marker for anaerobic glycolytic potential, decreased about 50% in activity as the sampling depth increased from 1 to 8 cm. 8. In summary, the superficial portion of the equine gluteus medius was found to be more glycolytic and less aerobic in its metabolic profile than deeper regions. The muscle became progressively more aerobic and less glycolytic with increasing sampling depth.
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PMID:Changes in the metabolic profile of the equine gluteus medius as a function of sampling depth. 290 49

We have investigated (a) effects of varying proton concentration on force and shortening velocity of glycerinated muscle fibers, (b) differences between these effects on fibers from psoas (fast) and soleus (slow) muscles, possibly due to differences in the actomyosin ATPase kinetic cycles, and (c) whether changes in intracellular pH explain altered contractility typically associated with prolonged excitation of fast, glycolytic muscle. The pH range was chosen to cover the physiological pH range (6.0-7.5) as well as pH 8.0, which has often been used for in vitro measurements of myosin ATPase activity. Steady-state isometric force increased monotonically (by about threefold) as pH was increased from pH 6.0; force in soleus (slow) fibers was less affected by pH than in psoas (fast) fibers. For both fiber types, the velocity of unloaded shortening was maximum near resting intracellular pH in vivo and was decreased at acid pH (by about one-half). At pH 6.0, force increased when the pH buffer concentration was decreased from 100 mM, as predicted by inadequate pH buffering and pH heterogeneity in the fiber. This heterogeneity was modeled by net proton consumption within the fiber, due to production by the actomyosin ATPase coupled to consumption by the creatine kinase reaction, with replenishment by diffusion of protons in equilibrium with a mobile buffer. Lactate anion had little mechanical effect. Inorganic phosphate (15 mM total) had an additive effect of depressing force that was similar at pH 7.1 and 6.0. By directly affecting the actomyosin interaction, decreased pH is at least partly responsible for the observed decreases in force and velocity in stimulated muscle with sufficient glycolytic capacity to decrease pH.
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PMID:Effects of pH on contraction of rabbit fast and slow skeletal muscle fibers. 296 65

The goal was to describe the metabolic profile of ganglionic and cortical arteries and arterioles in aging normotensive male rats. Five enzymes indicative of key metabolic pathways in the vessel walls were semiquantitatively evaluated using bright-field histochemical microscopy. Lactate dehydrogenase showed significant reactivity which increased with vessel diameter in cortical and ganglionic vessels in all age groups tested. Succinate dehydrogenase and cytochrome oxidase showed little reactivity in both cortical and ganglionic vessels, suggesting a reduced role for aerobic metabolic pathways. Myosin ATPase reactivity was high in cortical and ganglionic vessels. Only this enzyme showed an increased reactivity that was correlated with the age and diameter of the vessel. Glucose-6-phosphate dehydrogenase reactivity was more pronounced in cortical than ganglionic vessels, suggesting that the hexose-monophosphate-shunt may be more active in the cortical vessels. There were no regional differences in enzyme reactivity throughout the caudatoputamen. In conclusion, both the cortical and ganglionic vessels are metabolically active, with significant anaerobic glycolysis, and reduced, but observable capacity for aerobic metabolism. The decreased myosin ATPase reactivity and the low level of glucose-6-phosphate dehydrogenase reactivity in the ganglionic arterioles of senescent rats may contribute to the susceptibility of these vessels to cerebrovascular accidents.
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PMID:A histochemical study of cerebral cortical vessels and ganglionic vessels of the caudatoputamen in aging normotensive rats. 315 35