Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A purified preparation of Ascaris myosin was obtained from the muscle layer of Ascaris lumbricoides suum, using gel filtration and ion-exchange chromatography. 2. Ascaris myosin whether purified or unpurified, had almost the same ability for ATP-splitting and superprecipitation. 3. Ascaris myosin and rabbit skeletal myosin were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A significant difference in the number of light chains between both myosins was found. Ascaris myosin was found to have one heavy chain and two distinct light chain components (LC1-A and LC2-A), having molecular weights of 18000 and 16000, respectively. These light chains correspond in molecular weight to the light chain 2 (LC2-S) and light chain 3 (LC3-S) in rabbit skeletal myosin. 4. LC1-A could be liberated from the Ascaris myosin molecule reacted with 5,5'-dithio-bis(2-nirobenzoic acid( Nbs2) with recovery of ATPase activity by addition of dithiothreitol. These properties are equivalent to those of the LC2-S in rabbit skeletal myosin, although Ascaris myosin when treated with Nbs2-urea lost its ATPase activity.
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PMID:Studies on the subunits of myosin from muscle layer of Ascaris lumbricoides suum. 12 18

Whereas dissociation of rabbit skeletal muscle myosin light chains occurs at an increased temperature (25 degrees) and in the absence of divalent cations, reassociation of the myosin oligomer requires a low temperature (4 degrees C) and the presence of divalent cations, thus resulting in the original light to heavy chain stoichiometry. With a 5-10 per cent release of alkali light chains, LC1 and LC3, and a 50 per cent dissociation of the Ca2+ binding light chain, LC2, there is no significant decrease in myosin ATPase activity irrespective of the cation activator, however, there is an approximate 15-20 per cent decrease in actomyosin ATPase activity. With reassociation of the myosin oligomer, actomyosin ATPase activity is partially restored as well as the original number of Ca2+ binding sites.
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PMID:Dissociation and reassociation of rabbit skeletal muscle myosin. 16 9

Skeletal muscle fibers from muscular dystrophic mice (C57BL/10-mdx) 1-4 months of age show elevated free Ca2+ concentrations both at resting and stimulated states, although contractility of adult (2-12 months old) mouse is similar to that of normal mouse. To evaluate the sensitivity of the contractile system of adult mdx mouse muscle to elevated free Ca2+ concentration, Mg2(+)-adenosine triphosphatase (ATPase) activity was examined using myosin, myosin B, and reconstituted actomyosin. Myosin Mg2(+)-ATPase activity of the mdx mouse was significantly higher than that of the normal mouse. Myosin B ATPase activity of the mdx mouse was also higher than that of normal mouse in free Ca2+ concentrations between 10(-9) and 10(-5) M, though there was no difference in the Ca2+ concentration required for half maximal activation of ATPase activity, 2 x 10(-7) M. Polymerized actin (FA) isolated from normal and mdx mice activated rabbit myosin Mg2(+)-ATPase identically, while activation of Mg2(+)-ATPase in mdx myosin by rabbit FA was significantly lower than that in normal mouse myosin. Rapid Pi liberation by Mg2(+)-ATPase in mdx mouse myosin was about half that of normal mouse myosin, being consistent with low activation of Mg2(+)-ATPase activity by rabbit FA. Polyacrylamide gel electrophoresis in the presence of pyrophosphate showed that myosin molecules of mdx and normal mice were both composed of three isozymes, although the fast migrating myosin isozyme (M1) was decreased while the slow migrating band (M3) was increased in mdx myosin. Subunit composition of myosin analyzed by polyacrylamide gel electrophoresis in the presence of SDS showed that the content of the smallest light chain (LC3) in mdx myosin was lower than that of normal mouse myosin, which agreed with findings that mdx myosin contained less M1 isozyme than normal myosin. These results indicated that the lowered response of mdx muscle fibers to elevated Ca2+ concentration can be attributed to the isozyme composition of myosin in mdx mouse.
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PMID:Kinetic properties and isozyme composition of myosin in the mdx mutant mouse. 214 75

Response of tenotomized rat soleus muscle to denervation performed at different time intervals, has been investigated. Tenotomized muscles showed typical central core lesions seven days post-operatively. These were not observed in m-ATPase stained sections of simultaneously denervated and tenotomized muscles, and muscles denervated 24 h after tenotomy. Central core lesions were not prevented in muscles denervated 28 h after tenotomy, indicating that tenotomy effects responsible for central lesions are completed by this time. Myosin light chain pattern of muscles denervated 28 h after tenotomy, and tenotomized only were similar showing increased LC3/LC1 ratio. Simultaneously denervated and tenotomized muscle however showed all the three light chains relatively equal in quantity. The results suggest that elimination of neural activation within 28 h prevents myofibrillar loss and minimized other changes which occur due to tenotomy.
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PMID:Modifications in the histochemical and biochemical changes in tenotomized rat soleus by denervation. 374 79

Long-term intermittent stimulation (10 Hz, 8 h/day, 7 wk) of the fast-twitch tibialis anterior results in a complete transformation of type IIB fibers to type IIA fibers. This is shown by the histochemical ATPase reaction and by a decrease in Ca2+-uptake ability by the sarcoplasmic reticulum. Furthermore, as shown by studies on bulk myosin and on single fibers, the LC1-to-LC3 light chain ratio is increased on sodium dodecylsulfate gel electrophoretograms, and there are changes in the myosin isozyme pattern manifested on pyrophosphate gels under nondissociating conditions. Thus the staining intensity of the slower moving putative LC1 homodimer band increases, and there is a difference in migration velocity between stimulated and unstimulated isozymes suggesting a possible difference in the heavy chain. This study underlines the importance of the stimulation schedule in determining whether a fast-to-slow transformation or a shift in subtype takes place.
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PMID:Type IIB to IIA fiber transformation in intermittently stimulated rabbit muscles. 621 Nov

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

It is shown that myosin of human skeletal muscles is more difficult for purification from the actin and nucleic acids admixtures. It is also characterized by a less yield and a pronounced lability to denaturant effects as compared to rabbit myosin. The ATPase activity of human myosin is 1.5-2 times as low and the cholinesterase one--tens of times as high as those of rabbit myosin. A relative content of LC3 (LC--light chains) is approximately twice as low and that of LC1--as high as in rabbit myosin. It is supposed that the found differences in the properties may be explained to a considerable extent by a different ratio of certain light chains contained in the investigated proteins.
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PMID:[Subunit composition and enzymatic properties of myosins from human and rabbit skeletal muscles]. 621 80

Actomyosin complex was extracted from the brain cortex in a medium consisting of low salt, ATP, and EDTA, in the presence of protease inhibitors, followed by ammonium sulfate fractionation. Myosin was then purified from the actomyosin. Myosin obtained according to the procedure used was significantly contaminated with actin high (greater than 200,000 dalton) and low molecular weight proteins. Therefore, an alternative method based on affinity chromatography (Blue Dextran/Sepharose) and gel filtration (Sepharose 4B) was developed to purify myosin. This procedure yielded myosin that was greater than 95% pure as judged by electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The subunit composition of purified brain myosin was monitored by sodium dodecyl sulfate-polyacrylamide gel also containing a urea gradient. A closely migrating triplet in the heavy chain and three light chains, LC1, LC2, and LC3, of Mr 21,000, 19,000, and 17,000, respectively, were observed. These findings raise the possibility of the existence of myosin isoenzymes in the brain. Brain myosin formed bipolar thick filaments in 0.075 M KCl and MgCl2. At low ionic strength, the Mg2+-ATPase activity of myosin was stimulated 3- to 3.5-fold in the presence of skeletal muscle f-actin. Brain myosin also hydrolyzed other nucleotides; the rate of hydrolysis was ITP greater than ATP approximately equal to CTP greater than GTP approximately equal to UTP. The substrate (ATP) saturation curve in the presence of 10 mM CaCl2 and 0.6 M KCl was complex and consisted of plateau regions. The Arrhenius plot of the Ca-ATPase data was linear, whereas with ITPase, it was biphasic with a break occurring around 20 degrees C.
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PMID:Purification and characterization of myosin from calf brain. 622 62

Sarcoplasmic and myofibrillar proteins of a frog mixed muscle (distal cruralis bundle) were investigated and compared to their fast twitch muscle homologues. Histochemical reactions revealed two populations of fibres in this muscle, differing from fast twitch fibres by the intensity of their myofibrillar ATPase reaction and by their mitochondrial NADH dehydrogenase activity. The distribution of parvalbumins and LDH isoenzymes in the whole muscle showed some features of tonic muscle type. Myosin light chains pattern of cruralis bundle fibres was characterized by the lower proportion of the LC3 subunit. These results confirmed the heterogeneity of this frog muscle and the presence of tonic or intermediate fibres with their typical sarcoplasmic and myofibrillar proteinic composition.
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PMID:Comparison of the sarcoplasmic and myofibrillar proteins of twitch and tonic fibres of frog muscle (Rana esculenta). 644 68

Myosin from distal cruralis bundle of triceps femoris composed of slow-tonic and fast-twitch fibers in an about 1 to 1 ratio, from rectus abdominis containing a lower proportion of slow-tonic fibers, and from a fast-twitch sartorius muscle of the frog, was characterized by means of polyacrylamide gel electrophoresis in the presence of sodium dodecylsulphate (SDS), electrophoresis in non-dissociating conditions, and determination of the ATPase activity. SDS-polyacrylamide gel electrophoresis failed to reveal the presence of any specific light chain in myosin from slow-tonic fibers. Light chains having the same mobilities as fast-twitch LC1 and LC2 were observed; as previously described by Focant and Reznik [15], myosin from tonic fibers appears, on the other hand, devoid of LC3. By electrophoresis in non-dissociating conditions myosin from sartorius muscle was resolved into three components which comigrated with the three myosin isoenzymes from the fast-twitch posterior latissimus dorsi muscle of the chicken. Preparations from rectus abdominis and from cruralis bundle were shown to contain an additional component of lower electrophoretic mobility. Its relative proportion in these two muscles suggests that it represents the slow-tonic fiber myosin isoenzyme. Analysis of proteolytic digestion patterns revealed differences in the heavy chain structure of the isoenzymes from slow and fast fibers, respectively. As indicated by ATPase measurements, fast-twitch myosin exhibits a higher catalytic activity than myosin from slow-tonic fibers, the difference being of the same order as that reported for myosins from slow and fast muscles of higher vertebrates.
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PMID:Comparison of myosin isoenzymes from slow-tonic and fast-twitch fibers of frog muscle. 645 9


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