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)

In the present investigation the results of a lead salt technique and two calcium salt techniques for the deomonstration of the activity of myosin adenosine triphosphatase in sections of both normal and pathological human skeletal muscle specimens are compared. It was seen that the histochemical results obtained by the different techniques are similar, especially with regard to the identification of fibre-types. It can be clearly stated, that the alkaline phosphatase activity present in muscle fibers of diseased skeletal msucles revealed only a very slight activity with the substrate ATP, so the alkaline phosphatase activity in general did not disturb the reliability of the different myosin ATPase techniques. Moreover it was found that the presence of the mitochondrial Ca2+ -ion activated ATPase with a high pH-optimum in muscle fibers did not give rise to faulty results. From studies with dinitrophenol it can be concluded that this substance activates the myosin ATPase present in type I fibres especially.
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PMID:The value of enzyme histochemical techniques in the classification of fibre types of human skeletal muscle. 2. The histochemical demonstration of myosin adenosine triphosphatase in skeletal muscles from adult patients with or with no diseases of the neuromuscular system. A comparison between results obtained by calcium salt and lead salt techniques. 14 Aug 52

Capillary supply, the proportion of oxidative fibres and blood flow were studied in fast rat muscles (tibialis anterior, TA, and extensor digitorum, EDL) made ischaemic by ligation of the common iliac artery, in chronically stimulated muscles and in ischaemic chronically stimulated muscles. Stimulation was carried out for 6 h/day at 10 Hz (three periods of 2 h with 90-120-min intervals between stimulations) for 10-12 days using electrodes implanted in the vicinity of the lateral popliteal nerve. Blood flow (measured by radioactive microspheres) was 3.62 +/- 0.52 ml.100 g-1.min-1 at rest and 78.4 +/- 14.6 ml.100 g-1.min-1 (mean +/- SEM) during isometric contractions at 4 Hz. Ischaemic muscles had significantly lower blood flow at rest as well as during contractions (72 +/- 14% and 25 +/- 4% of the values in contralateral muscles respectively). Stimulated muscles had significantly higher flow than contralateral control muscles during contractions; stimulated ischaemic muscles had normal blood flow at rest, but the increase in flow during contractions was limited to a similar extent to that in ischaemic muscles alone. Of all anatomically present capillaries (staining for alkaline phosphatase in frozen sections) the capillary/fibre ratio increased by 36% in stimulated tibialis anterior, but was not significantly different from control muscles in stimulated ischaemic TA and was even lower than in control muscles in stimulated ischaemic EDL. The proportion of fast oxidative fibres (estimated on the basis of histochemical staining for myosin ATPase and succinate dehydrogenase) increased from 53.2 +/- 3.2% in normal EDL to 82.0 +/- 2.3% in chronically stimulated EDL and to 100% in chronically stimulated ischaemic muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The role of blood flow and/or muscle hypoxia in capillary growth in chronically stimulated fast muscles. 170

Muscle performance and structure was studied in rat soleus muscle with limited blood supply in combination with chronic muscle stimulation. Blood supply to the lower leg was restricted by ligation of the common iliac artery, electrodes were implanted in the vicinity of the sciatic nerve and ankle flexors were denervated. Three days later, soleus and gastrocnemius muscles were stimulated at 4 Hz four times a day for a period of 20 min with 2 h intervals between stimulations; this procedure was continued for 4 days. Muscle performance, histochemistry and ultrastructure were studied on the eighth day after operation in these muscles and in ischaemic unstimulated muscles with denervated ankle flexors. Both were compared with control animals. Muscles with limited blood supply developed less isometric twitch tension than control muscles (peak twitch tension in ischaemic muscle was 60.3 +/- 4.8 g g-1 muscle, mean +/- S.E.M., compared to 79.7 +/- 6.9 g g-1 in control muscle; tensions after 5 min contraction were 54.5 +/- 5.5 g g-1 in ischaemic muscle compared to 70.6 +/- 6 g g-1 in controls). Stimulated muscles with limited blood supply had higher peak (85 +/- 16.6 g g-1) and final (87 +/- 12 g g-1) tensions, and also fatigued less than muscles with limited blood supply but no stimulation. Histochemical estimation of capillary density (by staining for alkaline phosphatase) and slow (SO) and fast (FOG) fibres (by myosin ATPase staining) revealed similar capillary to fibre ratios (2.5) and a similar proportion of FOG fibres (around 18%) in all muscles. The proportion of glycogen-depleted fibres (estimated from the periodic acid Schiff reaction, PAS) in muscles removed from animals 10 min after a 5 min period of isometric twitches was significantly lower in ischaemic muscles (45.1 +/- 1.9%) than in control (80.5 +/- 1.5%) or chronically stimulated ischaemic muscles (67.3 +/- 4.0%). Electron microscopy showed disorganised myofibrils with Z-line streaming in 7.48 +/- 3.04% of fibres in muscles with limited blood supply. Swollen and degenerated mitochondria, dilated sarcoplasmic reticulum and areas of disrupted sarcolemma were also observed. Stimulated ligated muscles showed a significantly lower proportion of fibres with disorganised filaments (0.65 +/- 0.32%) and other signs of damage were much less frequent. The reduced damage and improved performance of chronically stimulated slow muscle may be the result of improved microcirculation, preventing accumulation of lactate.
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PMID:Effect of activity on performance and morphology in ischaemic rat slow muscles. 223 Jun 37

When 1 mM ATP is added to human dermal fibroblasts (DF) in monolayer culture permeabilized by glycerol, they undergo a rapid reduction in length and their intracellular actin filaments aggregate. This process is referred to as cell contraction. Treating glycerol-permeabilized DF with alkaline phosphatase before adding 1 mM ATP should cause dephosphorylation. Dephosphorylated preparations do not undergo cell contraction initiated by ATP. When myosin light-chain kinase (MLCK) isolated from turkey gizzard is added with cofactors to cells dephosphorylated by alkaline phosphatase treatment, contraction is restored. DF incubated for 24 h with db cAMP or cholera toxin show elevated intracellular concentrations of cAMP and little cell contraction. Contraction is reestablished when MLCK with cofactors is incubated with these preparations before ATP is added. Fibroblasts from Epidermolysis Bullosa dystrophica recessive patients produce excess cAMP. Those cells show minimal contraction, however; treating them with MLCK and cofactors renews contraction brought about by ATP. When DF are incubated with trifluoperazine to block calmodulin-dependent enzyme reactions, cell contraction is inhibited. Adding cytochalasin B disrupts microfilaments and also inhibits contraction. This work supports the idea that myosin ATPase is critical to cell contraction. Myosin ATPase is dependent on the phosphorylation of the regulatory peptide, myosin light chain. Elevating intracellular concentrations of cAMP or treatment of permeabilized cell preparations with alkaline phosphatase may inhibit myosin ATPase activity. The restoration of phosphorylation by adding MLCK with cofactors served to reestablish cell contraction.
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PMID:ATP-induced cell contraction in dermal fibroblasts: effects of cAMP and myosin light-chain kinase. 301 87

This communication presents the results obtained in tubular aggregates of 24 enzyme histochemical techniques for demonstrating activity of oxidoreductases, transferases, hydrolases and isomerases. The activity characteristics of the tubular aggregates in m. gluteus medius of 18 patients with diseases of the neuromuscular system were almost identical. A high activity of the mitochondrial enzymes, NADPH: tetrazolium oxidoreductase, NADH:tetrazolium oxidoreductase and cytochrome c oxidase, could be shown in the pathological structures, whereas the activity of the mitochondrial enzymes, glycerol-3-phosphate:menadione oxidoreductase, succinate:PMS oxidoreductase, malate:NAD+ oxidoreductase and isocitrate:NAD+ oxidoreductase, and the partial mitochondrial enzymes, malate:NADP+ oxidoreductase and isocitrate:NADP+ oxidoreductase, was very slight or even absent. There was a moderate to strong activity of the glycolytic enzymes lactate:NAD+ oxidoreductase, glyceraldehyde-3-phosphate:NAD+ oxidoreductase, phosphofructokinase, phosphoglucomutase and glucose phosphate isomerase. In contrast, the activity of alpha-glucan phosphorylase was slight. The activity of phosphogluconate:NADP+ oxidoreductase, glucose-6-phosphate:NADP+ oxidoreductase and 5'-nucleotidase was slight, whereas there was no activity of myosin ATPase and mitochondrial ATPase, acid phosphatase or alkaline phosphatase. The high activity of AMP-deaminase was very striking. The activity of peroxidase was moderate. Results obtained with adsorption studies point to adsorption of some of the enzymes studied to the tubular aggregates in vivo and this phenomenon very probably determined the histochemical characteristics of these structures.
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PMID:Histochemical features of tubular aggregates in diseased human skeletal muscle fibres. 317 98

Myosin purified from a murine myeloid leukaemia cell line (M1) that had been incubated with [32P]orthophosphate incorporated 32P into the heavy, but not the light, chain. When the heavy chain was dephosphorylated by bacterial alkaline phosphatase, myosin that had low actin-activated ATPase activity gained higher activity only in the presence of the light-chain kinase. In the absence of the light-chain kinase, however, the Mg2+-stimulated ATPase activity of myosin was not activated by actin, regardless of phosphatase treatment. These results indicate that the activity of M1 myosin ATPase is regulated by phosphorylation of both the light and heavy chains. A scheme for this regulation by phosphorylation is presented and discussed.
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PMID:Phosphorylation of the myosin heavy chain. Its effect on actin-activated Mg2+-stimulated ATPase in leukaemic myeloblasts. 613 30

Predominantly fast skeletal muscles of rabbits [tibialis anterior (TA), extensor digitorum longus (EDL)] were stimulated at a frequency naturally occurring in nerves to slow muscles (10 Hz continuously) for 8 h/day for 2--4 days. Such stimulation is known to convert all glycolytic fibers to oxidative and to increase capillary density. Our aim was to study early stages of conversion to investigate the factors responsible for the changes. Staining of quick-frozen sections for myosin ATPase, succinic dehydrogenase, and alkaline phosphatase was used to study the distribution of different fiber types and to measure fiber cross-sectional areas, capillaries per square millimeter, and capillary-to-fiber ratios in each fiber category. TA but not EDL showed conversion of fast glycolytic to fast oxidative fibers after 2 days, more after 4 days of stimulation. In both muscles, the largest fast glycolytic fibers were diminished in number after stimulation. There was significant increase in total capillaries per square millimeter after 4 days and some increase after 2 days of stimulation. The increase in capillaries per square millimeter exceeded the increase in the number of fibers per square millimeter, and since there was no change in mean fiber area, the increase is attributed to capillary growth. In EDL, there was an increase in the number of capillaries supplying both fast glycolytic and fast oxidative fibers, suggesting that capillary growth precedes fiber type conversion. In TA, the number of capillaries supplying fast oxidative fibers was increased but that to fast glycolytic fibers, was not. This is consistent with capillary growth simultaneous with or following fiber conversion. In both TA and EDL the number of capillaries perfused after contraction was higher in stimulated muscles, suggesting that increased capillary flow contributed to capillary growth.
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PMID:Early changes in fiber profile and capillary density in long-term stimulated muscles. 621 58

The ribose-modified chromophoric and fluorescent analog of ATP 2',3'-O-(2,4,6-trinitrocyclohexadienylidene) adenosine 5'-triphosphate (TNP-ATP) has been synthesized previously (Hiratsuka, T., and Uchida, K. (1973) Biochim. Biophys. Acta 320, 635-647 and Hiratsuka, T. (1976) Biochim. Biophys. Acta 453, 293-297). In the present study, four TNP-derivatives of ATP, ADP, AMP and adenosine were synthesized and compared for several chemical, spectral and enzymatic properties. Their visible absorption and fluorescent properties were found to be quite similar. Visible absorption and fluorescence spectra of TNP-derivatives were sensitive to solvent polarity. TNP-adenosine and TNP-AMP showed considerable substrate activities with adenosine deaminase and alkaline phosphatase, respectively. TNP-ATP proved to be an excellent substitute for ATP in adenylate kinase and myosin ATPase systems. The results indicate that these analogs are useful as chromophoric and fluorescent probes for hydrophobic regions in adenine nucleoside and nucleotide requiring enzymes.
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PMID:Biological activities and spectroscopic properties of chromophoric and fluorescent analogs of adenine nucleoside and nucleotides, 2',3'-O-(2,4,6-trinitrocyclohexadienylidene) adenosine derivatives. 629 7

Dictyostelium myosin is composed of two heavy chains and two pairs of light chains in a 1:1:1 stoichiometry. Myosin purified from amoebae grown in medium containing [32P]phosphate had two of the subunits labeled (0.2-0.3 mol of phosphate per mol of 210,000-dalton heavy chains and approximately 0.1 mol of phosphate per mol of 18,000-dalton light chain). Kinase activities specific for the 210,000-dalton and for the 18,000-dalton subunits have been identified in extracts of Dictyostelium amoebae, and the heavy chain kinase has been purified 50-fold. This kinase phosphorylated Dictyostelium myosin to a maximum of 0.5-1.0 mol of phosphate per mol of heavy chain. Heavy chain phosphate, but not light chain phosphate, can be removed with bacterial alkaline phosphatase. Actin-activated myosin ATPase increased 80% when phosphorylated myosin was dephosphorylated to a level of approximately 0.06 mol of phosphate per mol of heavy chain. This effect could be reversed by rephosphorylating the myosin. The ability of myosin to self-assemble into thick filaments was inhibited by heavy chain phosphorylation. For example, in 80-100 mM KCl, only 10-20% of the myosin was assembled into thick filaments when the heavy chains were fully phosphorylated. Removal of the heavy chain phosphate resulted in 70-90% thick filament formation. This effect on self-assembly could be reversed by rephosphorylating the dephosphorylated myosin. These findings suggest that heavy chain phosphorylation may regulate cell contractile events by altering the state of myosin assembly.
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PMID:Regulation of myosin self-assembly: phosphorylation of Dictyostelium heavy chain inhibits formation of thick filaments. 645 32

To elucidate the clinical and histopathological features associated with autoantibodies to the signal recognition particle (SRP), we have studied 23 Japanese patients with this specificity among 3,500 patients with polymyositis/dermatomyositis and other connective tissue diseases. Anti-SRP antibodies were determined based on analysis of RNA and protein components by immunoprecipitation assays. The pathological analysis was performed by using special stainings including alkaline phosphatase, myosin ATPase, and modified Gomori trichrome stainings. Twenty-one (92%) of these 23 patients had myositis, 8 of whom (38%) required cytotoxic agents or intravenous immunoglobulin therapy in addition to corticosteroid therapy. Four patients (16%) had rheumatoid arthritis, two of whom had no features of myositis. Muscle biopsy specimens of 11 patients were examined histologically in detail. All 11 had muscle fiber necrosis and/or regeneration, but only one had infiltration of inflammatory cells. Six of the 11 (55%) patients showed type I fiber predominance by ATPase staining, while eight control myositis patients without anti-SRP antibodies did not. There was no correlation of other neurogenic features in histology with the presence of anti-SRP antibodies. These studies suggest that anti-SRP autoantibodies are most likely to be related to myopathies that are resistant to corticosteroid therapy and without inflammation histopathologically.
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PMID:Clinical and histopathological features of myopathies in Japanese patients with anti-SRP autoantibodies. 1908 33


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