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)

We measured the interrelationships between ventricular muscle myosin mass, myosin ATPase activity and collagen in cats with varying degrees of hypertrophy from left ventricular (LV) pressure-overload produced by either aortic banding or renal hypertension. In order to compare two models of LV pressure-overload with different time courses of progression, the results were analyzed as a function of LV mass or LV weight/body weight (LV/BW) ratio. Myosin was quantitated by SDS-polyacrylamide gel electrophoresis and hydroxyproline was measured as an index of collagen. Myosin concentration was positively correlated with increasing LV mass in control cats. However, in pressure-overloaded LV, myosin concentration was elevated and nearly constant for LV less than 9.0 g, but decreased in LV greater than 9.0 g. Myosin concentration in pressure-overloaded LV was greatest before a significant increase in LV/BW ratio. Hydroxyproline concentration was inversely related to myosin concentration in both LV pressure-overload models and increased with the severity of hypertrophy. Actomyosin ATPase activity in pressure-overloaded LV, was not significantly different from control over a wide range of LV/BW ratios. However, absolute myosin ATP hydrolysis in pressure-overloaded LV, increased by as much as 40%, relative to control, due primarily to increased myosin. The changing spectrum and interrelationships of myosin and collagen were independent of the mechanism of pressure-overload, but were correlated with the severity of hypertrophy.
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PMID:Myocardial changes during the progression of left ventricular pressure-overload by renal hypertension or aortic constriction: myosin, myosin ATPase and collagen. 295 26

In order to gain some information regarding Ca2+-dependent ATPase, the enzyme was purified from cardiac sarcolemma and its properties were compared with Ca2+-ATPase activity of myosin purified from rat heart. Both Ca2+-dependent ATPase and myosin ATPase were stimulated by Ca2+ but the maximal activation of Ca2+-dependent ATPase required 4 mM Ca2+ whereas that of myosin ATPase required 10 mM Ca2+. These ATPases were also activated by other divalent cations in the order of Ca2+ greater than Mn2+ greater than Sr2+ greater than Br2+ greater than Mg2+; however, there was a marked difference in the pattern of their activation by these cations. Unlike the myosin ATPase, the ATP hydrolysis by Ca2+-dependent ATPase was not activated by actin. The pH optima of Ca2+-dependent ATPase and myosin ATPase were 9.5 and 6.5 respectively. Na+ markedly inhibited Ca2+-dependent ATPase but had no effect on the myosin ATPase activity. N-ethylmaleimide inhibited Ca2+-dependent ATPase more than myosin ATPase whereas the inhibitory effect of vanadate was more on myosin ATPase than Ca2+-dependent ATPase. Both Ca2+-dependent ATPase and myosin ATPase were stimulated by K-EDTA and NH4-EDTA. When myofibrils were treated with trypsin and passed through columns similar to those used for purifying Ca2+-ATPase from sarcolemma, an enzyme with ATPase activity was obtained. This myofibrillar ATPase was maximally activated at 3-4 mM Ca2+ and 3 to 4 mM ATP like sarcolemmal Ca2+-dependent ATPase. K+ stimulated both ATPase activities in the absence of Ca2+ and inhibited in the presence of Ca2+. Both enzymes were inhibited by Na+, Mg2+, La3+, and azide similarly. However, Ca2+ ATPase from myofibrils showed three peptide bands in SDS polyacrylamide gel electrophoresis whereas Ca2+ ATPase from sarcolemma contained only two bands. Sarcolemmal Ca2+-ATPase had two affinity sites for ATP (0.012 mM and 0.23 mM) while myofibrillar Ca2+-ATPase had only one affinity site (0.34 mM). Myofibrillar Ca2+-ATPase was more sensitive to maleic anhydride and iodoacetamide than sarcolemmal Ca2+-ATPase. These observations suggest that Ca2+-dependent ATPase may be a myosin like protein in the heart sarcolemma and is unlikely to be a tryptic fragment of myosin present in the myofibrils.
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PMID:A comparative study of the rat heart sarcolemmal Ca2+-dependent ATPase and myosin ATPase. 296 55

Hearts of genetically myopathic male hamsters (BIO 53 : 58) were studied at 1 month, 2 months, 3 months, 4 to 5 months and 7 months of age. The time course of alterations in the cardiac myofibrillar ATPase activity, the relationship of myofibrillar ATPase activity to free [Ca2+], myosin ATPase activity and the distribution of heavy chain myosin isoenzymes were evaluated. Mg2+-Ca2+ ATPase activity of cardiac myofibrils in myopathics was increased in 4 month and 7 month-old hamsters. Elevated Mg2+ ATPase activity was found as early as in 2-month-old hamster. However, there was no loss in the regulation of the myopathic myofibrillar assembly as measured by the PCa response (10(-7) M to 10(-4) M Ca2+). Scans of SDS electrophoresis slab gels of cardiac myofibrillar proteins from control (C) and myopathic animals (M) did not show any differences at any age group (1, 4 and 7 months). There was a significant decrease in myosin Ca2+ ATPase activity and actin activated Mg2+-ATPase activity at 4 to 5 months and 7 months of age in the myopathic hearts. At all ages in normal and myopathic animals cardiac myosin consisted of three isoenzymes, V1, V2 and V3. At all ages in controls and at 1 to 3 months in myopathics, V1 predominated and the isoenzyme distribution was V1 greater than V2 greater than V3. However, in myopathics at 4 to 5 months, the distribution was V1 = V3 greater than V2 and at 7 months was V3 greater than V2 greater than V1. Our experiments suggest alterations in different components of the contractile protein system that occur at different stages of myopathy.
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PMID:Multiple cardiac contractile protein abnormalities in myopathic Syrian hamsters (BIO 53 : 58). 315 46

Human erythrocytes contain an Mr 200,000 polypeptide that cross-reacts specifically with affinity-purified antibodies to the Mr 200,000 heavy chain of human platelet myosin. Immunofluorescence staining of formaldehyde-fixed erythrocytes demonstrated that the immunoreactive myosin polypeptide is present in all cells and is localized in a punctate pattern throughout the cell. Between 20-40% of the immunoreactive myosin polypeptide remained associated with the membranes after hemolysis and preparation of ghosts, suggesting that it may be bound to the membrane cytoskeleton as well as being present in the cytosol. The immunoreactive myosin polypeptide was purified from the hemolysate to approximately 85% purity by DEAE-cellulose chromatography followed by gel filtration on Sephacryl S-400. The purified protein is an authentic vertebrate myosin with two globular heads at the end of a rod-like tail approximately 150-nm long, as visualized by rotary shadowing of individual molecules, and with two light chains (Mr 25,000 and 19,500) in association with the Mr 200,000 heavy chain. Peptide maps of the Mr 200,000 heavy chains of erythrocyte and platelet myosin were seen to be nearly identical, but the proteins are distinct since the platelet myosin light chains migrate differently on SDS gels (Mr 20,000 and 17,000). The erythrocyte myosin formed bipolar filaments 0.3-0.4-micron long at physiological salt concentrations and exhibited a characteristic pattern of myosin ATPase activities with EDTA, Ca++, and Mg++-ATPase activities in 0.5 M KCl of 0.38, 0.48, and less than 0.01 mumol/min per mg. The Mg++-ATPase activity of erythrocyte myosin in 0.06 M KCl (less than 0.01 mumol/min per mg) was not stimulated by the addition of rabbit muscle F-actin. The erythrocyte myosin was present in about 6,000 copies per cell, in a ratio of 80 actin monomers for every myosin molecule, which is an amount comparable to actin/myosin ratios in other nonmuscle cells. The erythrocyte myosin could function together with tropomyosin on the erythrocyte membrane (Fowler, V.M., and V. Bennett, 1984, J. Biol. Chem., 259:5978-5989) in an actomyosin contractile apparatus responsible for ATP-dependent changes in erythrocyte shape.
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PMID:Human erythrocyte myosin: identification and purification. 388 Jul 59

Actomyosin and myosin were isolated from rat fast muscles, differing in the percentage of fast oxidative glycolytic and fast glycolytic fibres. The dependence of actomyosin ATPase activity from these muscles on the pH corresponds to the previously found dependence of myofibrillar ATPase on the pH, followed histochemically. The myosins isolated from the tensor fascia latae muscle (fast glycolytic) and extensor digitorum longus and tibialis anterior muscles (predominantly fast oxidative glycolytic muscles) differ in the effect of mild acid pre-incubation on myosin ATPase activity. They do not contain the same amount of LC3 and also tryptic peptides of these myosins display a slightly different pattern, as revealed by SDS gel electrophoresis.
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PMID:Comparison of actomyosin and myosin from rat muscles with marked differences in the ratio of fast oxidative glycolytic and fast glycolytic muscle fibres. 621 53

Ovis aries masseter is a typical muscle consisting of slow-twitch fibres. The muscle homogeneity is well evidenced histochemically by the myosin ATPase reaction. The extraction and purification of myosin from sheep masseter is reported. After its centrifugation and dialysis followed by ion-exchange chromatography, the protein analysed on SDS polyacrylamide gels showed the usual pattern of slow myosin. The light-chain LC2 was present as a double band, a fact which has already been reported and which could be ascribed to SH group oxidation. From the present data sheep masseter can be considered a good source of slow myosin, and we have used it satisfactorily in the preparation of specific antibodies.
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PMID:[Extraction and purification of slow myosin from the masseter muscle of Ovis aries]. 621 29

The effects of running training on the structure and function of ventricular myosin of guinea-pigs were studied. No differences in body or heart weights could be detected but the heart-to-body weight relation increased significantly (P less than 0.05) in the trained group. Ca2+ activated and K+ activated ventricular myosin ATPase activities as well as the electrophoretic appearances (SDS-PAGE, pyrophosphate-PAGE) did not change after training. Guinea-pig ventricular myosin in nondissociating conditions showed one band migrating close to rat-V3 isomyosin. The myosins of the trained and untrained animals also showed no immunological difference as determined by the competitive ELISA-test: they both shared antigenic determinants common to rat-V1 isomyosin.
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PMID:Effects of treadmill running on the properties of guinea-pig myosin. 632 14

Although a previously reported analysis of Physarum myosin detected no cysteine residues in the molecule, the myosin ATPase activity was inhibited by p-chloromercuribenzoate. We have re-examined this apparently contradictory finding. We found highly purified plasmodial myosin to be very sensitive to N-ethylmaleimide inhibition of the K+, Ca2+ -activated ATPase. An estimate of the number of reactive sulfhydryls of the native myosin using Ellman's reagent showed only 1.5 mol 11 min-reactive sulfhydryl/mol as compared to 4.5 for chicken breast myosin in 5 min. 3H- and 14C-labelled N-ethylmaleimide was used to estimate the total sulfhydryls of the SDS-denatured heavy chains. Plasmodial myosin heavy chains bound 10-13% of the N-ethylmaleimide bound by chicken breast myosin heavy chains. Smooth muscle myosin heavy chains as well as heavy chains of embryonic chicken presumptive myoblasts had 65-70% of the reactive groups of chicken myotube myosin heavy chains. Amino acid analyses of purified Physarum myosin showed that some preparations contained cysteic acid residues even before performic oxidation. After the performic oxidation a mean value of 3 mol cysteic acid per 10(5) g Physarum myosin was found, or less than half that reported for striated muscle myosin. Our results show that in the sulfhydryl-poor plasmodial myosin each heavy chain contains at least two sulfhydryls, and probably more, but that there is variable oxidation of the total sulfhydryls. It has been reported that plasmodial myosin lacks rapidly reacting sulfhydryls groups when tested with an ATP analogue which reacts with light chains of vertebrate muscle myosins. Therefore, the 1-2 sulfhydryls of plasmodial myosin which react rapidly with Ellman's reagent appear to be on the heavy chain. Our results also suggest that during development of myotubes changes occur in the myosin heavy chains.
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PMID:Sulfhydryl groups of native myosin and of the myosin heavy chains from Physarum polycephalum compared to vertebrate skeletal, smooth, and non-muscle myosins. 705 79

The distribution of collagen fibers of rat masticatory muscles during the postnatal period (two weeks), was investigated by electrophoresis and immunohistochemistry. At these stages, the myosin of rat masticatory muscles displays specific electrophoretic patterns. Comparison of the myosin patterns of these muscles allows their identification. 1) Analysis by SDS-PAGE indicated that one of three weakly reactive stainable proteins with lower mobility than the heavy chain of myosin disappeared from the temporal muscle on day 13, as compared with other masticatory muscles. However, in histochemical analysis of the muscle fibers, the reaction specific for succinic dehydrogenase (SDH) activity was strong, and the fibers on day 13 could be classified into two types with respect to SDH activity. By contrast, on day 0, the fibers were classified into two types with respect to myosin ATPase activity. 2) Immunohistochemical analysis indicated that the distribution of the components of the extracellular matrix in the epimysium (type I collagen), perimysium (type I collagen, fibronectin, and laminin) and endomysium (type III collagen, fibronectin, laminin, and tenascin) was related to the metabolic capacity on days 12 to 13. The variability in the types of myosin and in proteins of the extracellular matrix might be important during the development of rat masticatory muscles.
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PMID:Distribution of the macromolecular components of masticatory muscles during differentiation of the muscle fibers in the postnatal rat. 857 Jan 40

Increased maximum velocity of shortening (Vmax), increased shortening ability (delta Lmax) and decreased relaxation rate have been reported for arterial smooth muscle from 16- to 18-week-old spontaneously, hypertensive rats (SHR) compared with age-matched normotensive Wistar-Kyoto rats (WKY). Vmax is dependent on actomyosin ATPase activity, and this activity is in turn dependent on the level of phosphorylation of the 20-kDa myosin light chain (MLC20) normally a function of calcium concentration. In this article, methods are described and data are presented from studies addressing possible intracellular regulatory mechanisms that might lead to the altered contractility of the SHR arterial muscle. In one study, myofibrillar protein was extracted from 16- to 18-week-old SHR and WKY caudal arterial muscle. The Mg(2+)-activated ATPase activity was measured under conditions where the Ca2+ concentration was controlled. In another study, the amount of myosin present and relative proportions of the myosin heavy chain (MHC) isoforms were determined by quantitative SDS-PAGE using heavy molecular weight standards and bovine serum albumin as the standard for concentration. In a third study, MLC20 phosphorylation levels in electrically stimulated arterial muscle were determined by urea glycerol gel electrophoresis and Western blot analyses. The SHR (n = 6) myofibrillar ATPase liberated 0.011 +/- 0.003 mumol Pi/mg myosin/min, which was significantly more than the 0.006 +/- 0.001 mumol Pi/mg myosin/min liberated by the WKY (n = 4) myofibrillar ATPase (P < 0.05). Consistent with the increased ATPase activity, phosphorylation of MLC20 was increased by 2.8 times as much in the SHR compared with the WKY electrically stimulated arterial muscle. However, there was no difference in MHC isoform pattern in the SHR compared with the WKY arterial muscle in contrast to the findings of at least one other laboratory. This discrepancy is discussed. The data reviewed in this article lead to the conclusions that an increased actin-activated myosin ATPase activity and MLC20 phosphorylation are likely responsible for the increased velocity of shortening previously reported in SHR arterial muscle and the increased ATPase activity is not a function of an increased myosin content or of altered MHC isoform pattern in the SHR muscle.
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PMID:Arterial muscle myosin heavy chains and light chains in spontaneous hypertension. 918 11


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