Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

1. Percutaneous needle biopsies were obtained from six limb muscles in six horses before and during a training programme of 10 or 15 weeks designed to involve both aerobic and anaerobic work. In a subsequent detraining period, biopsies were also taken after 5 and 10 weeks. 2. Samples were analysed biochemically for enzyme activity of lactic dehydrogenase (LDH), creatine phosphokinase (CPK), aldolase (ALD), citrate synthase (CS), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) and for glycogen content. Fibre typing was carried out histochemically before and 10 weeks after commencement of training. 3. There was a significant increase in the percentage of high myosin ATPase activity pH 9-4/high oxidative (FTH) fibres with a corresponding decrease in high myosin ATPase activity pH 9-4/low oxidative (FT) fibres and low myosin ATPase activity pH 9-4/high oxidative (ST) fibres after 10 weeks training. 4. During training, enzyme activities increased progressively but at different rates with an approximate twofold increase in all of the enzymes except CPK by the end of the training period. Changes in all the muscles studied were similar. Glycogen content increased by approximately 33% which was significant when all the muscles were considered together. 5. A decrease in enzyme activity occurred after 5 weeks detraining. However at 10 weeks a consistent but inexplicable increase in all enzyme levels, except CS again occurred. 6. It is concluded that training increased greatly the activity of enzymes involved in both aerobic and anaerobic metabolism.
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PMID:The effect of training and detraining on muscle composition in the horse. 14 28

Single muscle fibres were isolated by microdissection from freeze-dried samples of rabbit psoas and soleus muscles. The individual fibres were typed according to qualitative histochemical reactions for succinate dehydrogenase or NADH-tetrazolium reductase and for alkaline Ca2+-activated myofibrilla myosin ATPase after acid or alkaline preincubation. Methods are described for electrophoretic analysis by means of polyacrylamide disc electrophoresis in the presence of SDS of total myofibrilla proteins in single fibres after pre-extraction of soluble proteins. Fast-twitch white fibres revealed a myosin light chain pattern characteristic of "fast- type" myosin with three light chains of apparent molecular weights of 22,300 (LC1) 18,400 (LC2) and 16,000 (LC3). Fast-twitch red fibres were indistinguishable in this respect from fast-twist white fibres and showed an identical pattern of myosin light chains. Slow-twitch fibres could be characterized by a myosin light chain pattern typical of myosin of slow-twitch muscles with peptides of the apparent molecular weights of 23,500 (LC1Sa), 23,000 (LC1Sb) and 18,500 (LS2S). Slow-twitch fibres isolated from soleus as well as from psoas muscle were indistinguishable with regard to their myosin light chain patterns, thus suggesting that fibres of the same histochemical type correspond in their myosin light chain patterns irrespective of their origin from different muscles.
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PMID:Myosin light chain patterns of individual fast and slow-twitch fibres of rabbit muscles. 14 18

Re-innervated extensor digitorum longus, soleus and plantaris muscles of the rat were studied after denervation performed at various postnatal ages. The muscle fibres, which normally run from tendon to tendon as independent units, were found to be very frequently connected by myomuscular junctions, both in the form of terminal insertions of one fibre into another and of lateral bridges which may join two or more muscle fibres at one or more levels. Positive reaction for AChE activity was demonstrated at the level of the junctions. Incubation for myosin ATPase activity showed that myomuscular junctions are only found between fibres of the same histochemical type, which in re-innervated muscles are usually aggregated in 'type groupings'. Ultrastructural features were similar in both forms of myomuscular junctions. The appearance is that of an interdigitation of muscle projections from neighbouring fibres, each projection being covered by a basement membrane with attached collagen fibrils. The finger-like projections at their endings contain vesicles and elongated cisternae filled with granular dense material. It is postulated that the synchronous activity of neighbouring fibres within the compact motor units of reinnervated muscles is a causal factor initiating the formation of myomuscular junctions.
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PMID:Myomuscular junctions in re-innervated rat skeletal muscle. 14 21

Alteration in the histochemical activity of myosin ATPase has been demonstrated in the soleus of adult rats after brief (A) and prolonged (B) intensive weight lifting exercises. The former represented 'high intensity-short duration' and the latter 'high intensity-prolonged duration' exercise. The data revealed a significant muscle hypertrophy (23-26%) in both the exercising groups. Whereas group A muscles showed a relative increase in the number of type II (FOG) fibres, accompanied by a hypertrophy of the type I or slow twitch-oxidative (SO) fibres, the soleus muscles in group B showed a significant decrease (P less than 0.01) in the number of type II (FOG) fibres, presumably owing to a conversion of type II (FOG) to type I (SO) fibres. It is hypothesized that strengthening exercise may enhance the activity of the 'fast type' of myosin ATPase in brief or static work, and the 'slow type' in prolonged or more dynamic high intensity work.
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PMID:Myosin ATPase activity after strengthening exercise. 14 22

The moles of calcium bound by the left ventricle were 1.5 +/- 0.1, while those of the right ventricle were 2.9 +/- 0.2. The calcium binding constants were the same between myosins of the two cardiac ventricles. The Ca2+ binding constants were approximately 1.1 X 10(5) M-1 for both left and right ventricular myosins. Left ventricular myosin bound 1.3 +/- 0.1 mol of Mn2+, whereas right ventricular myosin bound 2.8 +/- 0.1 mol of Mn2+. The divalent cation Mn2+ only partially competed out Ca2+ (50%). Because of the partial competition, it seemed that Ca2+ and Mn2+ had some sights in common. These studies demonstrate a twofold difference in divalent cation binding (Ca2+, Mn2+) between left and right ventricular myosins. This variation in cation binding between the two ventricles is reflected in similar differences in myosin ATPase activity between the two ventricles.
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PMID:Binding of divalent cations by canine cardiac myosin: differences in normal right and left ventricles dependent upon number of light chains. 14 25

Human cardiac myosin isolated from operatively obtained samples of ventricular septum and left ventricular free wall of patients with asymmetric septal hypertrophy (ASH) was compared, with respect to structural and enzymatic properties, to myosin isolated from hearts of patients without heart disease. The following parameters were studied: 1) activation of myosin ATPase activity by K+-EDTA and Ca2+,2) molecular weight of the heavy and light chains of myosin as determined by electrophoretic migration in SDS-polyacrylamide gels, and 3) ability to form bipolar aggregates at low ionic strength, as examined by electron microscopy. No difference was present in any of these parameters between human cardiac myosin from patients with ASH and from patients without heart disease. Thus, the genetic defect present in patients with ASH is not expressed in the particular structural and functional characteristics of myosin evaluated in this study.
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PMID:Characterization of myosin from patients with asymmetric septal hypertrophy. 14 40

Cardiac muscle myosin ATPase activity is depressed and contractile function impaired when the heart is subjected to a chronic pressure overload. Administering digitalis in the presence of chronic pressure overload significantly attenuates the decline in mechanical function. The current study sought to determine if the cardiac muscle myosin ATPase activity of cats treated with digitalis in the presence of pressure overload remains normal in parallel with the mechanical function. Four groups of cats were studied: normal controls (C), animals with pressure-overload hypertrophy with or without failure (HF), normal cats that received treatment with digitalis (D), and animals that received digitalis prior to and together with pressure overload (DHF). Compared to C, the maximum myosin ATPase activity of HF was significantly (P less than 0.05) depressed, but the maximum ATPase activity of D and DHF was not altered significantly (P greater than 0.05) from C. In parallel with the enzyme maximum activity, the papillary muscle isometric rate of force development was significantly (P less than 0.005) depressed in HF compared to C; D and DHF were not significantly (P greater than 0.05) different from C. It is concluded that the depression of myosin ATPase observed in HF is not present when digitalis is administered concomitant with the pressure overload.
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PMID:Normal cardiac myosin ATPase and mechanics in pressure overload with digitalis treatment. 14 32

Preparations of ATP from equine muscle contained an inhibitor of dynein Mg2+-activated ATPase. The inhibitory material was separated from the ATP by molecular sieve filtration. The several molecular species of dynein extracted from three different axonemal sources were all inhibited; myosin ATPase was not. With increasing amounts of inhibitor the inhibition did not go to completion but reached a plateau when the rate had been reduced to 1/5 the uninhibited rate. A plot of 1/[S] against 1/v at several inhibitor concentrations yielded parallel lines. There was little inhibition of dynein ATPase when Mg2+ was replaced by Ca2+. The inhibitor appeared slightly smaller in molecular size than ATP, had anionic character, and was not adsorbed to charcoal.
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PMID:A dynein ATPase inhibitor isolated from a commercial ATP preparation. 14 8

The Mg2+-dependent ATPase (adenosine 5'-triphosphatase) mechanism of myosin and subfragment 1 prepared from frog leg muscle was investigated by transient kinetic technique. The results show that in general terms the mechanism is similar to that of the rabbit skeletal-muscle myosin ATPase. During subfragment-1 ATPase activity at 0-5 degrees C pH 7.0 and I0.15, the predominant component of the steady-state intermediate is a subfragment-1-products complex (E.ADP.Pi). Binary subfragment-1-ATP (E.ATP) and subfragment-1-ADP (E.ADP) complexes are the other main components of the steady-state intermediate, the relative concentrations of the three components E.ATP, E.ADP.Pi and E.ADP being 5.5:92.5:2.0 respectively. The frog myosin ATPase mechanism is distinguished from that of the rabbit at 0-5 degrees C by the low steady-state concentrations of E.ATP and E.ADP relative to that of E.ADP.Pi and can be described by: E + ATP k' + 1 in equilibrium k' - 1 E.ATP k' + 2 in equilibrium k' - 2 E.ADP.Pi k' + 3 in equilibrium k' - 3 E.ADP + Pi k' + 4 in equilibrium k' - 4 E + ADP. In the above conditions successive forward rate constants have values: k' + 1, 1.1 X 10(5)M-1.S-1; k' + 2 greater than 5s-1; k' + 3, 0.011 s-1; k' + 4, 0.5 s-1; k'-1 is probably less than 0.006s-1. The observed second-order rate constants of the association of actin to subfragment 1 and of ATP-induced dissociation of the actin-subfragment-1 complex are 5.5 X 10(4) M-1.S-1 and 7.4 X 10(5) M-1.S-1 respectively at 2-5 degrees C and pH 7.0. The physiological implications of these results are discussed.
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PMID:Reaction mechanism of the magnesium ion-dependent adenosine triphosphatase of frog muscle myosin and subfragment 1. 14 77

The nerve growth factor protein (NGF) favors polymerization of brain actin and induces its organization to form paracrystalline structures that activate myosin ATPase (ATP phosphohydrolase, EC 3.6.1.3) to an extent greater than actin alone. Binding studies show that the initial 1:1 stoichiometry of NGF-G-actin complexes decreases to 1:7-10 when polymerization is ended and paracrystalline structures are formed. The ratio becomes even lower when heavy meromyosin is added in the absence of ATP, suggesting that heavy meromyosin displaces NGF bound to actin microfilaments. This conclusion is supported by the finding that when heavy meromyosin is added to NGF-microfilament complexes, under conditions for "decorating" microfilaments, the usual paracrystalline structure of the complexes disappears. The NGF-mediated organization of actin and activation of myosin ATPase is visualized as a self-regulatory and self-propagating mechanism, because progressive displacement of the growth factor induced by heavy meromyosin binding to F actin as ATP consumption proceeds renders an increasingly higher amount of NGF free for new interactions. These findings are discussed in the light of the mechanism of action of NGF in the target cells.
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PMID:Nerve growth factor potentiates actomyosin adenosinetriphosphatase. 14 85


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