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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myosin was purified from rabbit alveolar macrophages in a form that could not be activated by actin. This myosin could be phosphorylated by an endogenous myosin light chain kinase, up to 2 mol of phosphate being incorporated/mol of myosin. The site phosphorylated was located on the 20,000-dalton myosin light chain. Phosphorylation of macrophage myosin was found to be necessary for actin activation of myosin ATPase activity. Moreover, the actin-activated ATPase activity was found to vary directly with the extent of myosin phosphorylation, maximal phosphorylation (2 mol of Pi/mol of myosin) resulting in an actin-activated MgATPase activity of approximately 200 nmol of Pi/mg of myosin/min at 37 degrees C. These results establish that phosphyoyration of the 20,000-dalton light chain of myosin is sufficient to regulate the actin-activated ATPase activity of macrophage myosin.
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PMID:Macrophage myosin. Regulation of actin-activated ATPase, activity by phosphorylation of the 20,000-dalton light chain. 15 17

Myosin isolated under phosphorylation conditions, showed an additional band of phosphorylated light chain. In the case of cardiac myosin, LC2 is the phosphorylated light chain whereas in skeletal myosin, it is the 18,000 dalton component known as DTNB light chain. There are no differences in K+-EDTA and Ca2+ activated myosin ATPase of cardiac and skeletal of control and phosphorylated myosins. Our experiments showed that the rat heart and skeletal muscle myosins isolated under phosphorylating conditions exhibited high phosphate content which is associated with higher actin activated Mg2+ ATPase activity of myosin as compared to control. Control myosin phosphorylated using myosin light chain kinase and Ca2+ also showed high actin activated myosin ATPase activity. Beef heart myosin isolated in the presence of phosphate buffer, also exhibited a higher level of phosphate followed by an increase in actin activation as compared to myosin isolated in the absence of phosphate buffer. All these experimental data suggest that there is a direct relationship between actin activation and the amount of phosphate incorporated as a result of phosphorylation.
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PMID:Phosphorylation and its effects on ATPase activity of cardiac and skeletal myosins. 16 48

Mild pulmonic stenosis in the dog, where right ventricular peak systolic pressure was increased approximately 150% at the time of sacrifice, induced 100% or more increase in right ventricular free wall weight by 3 weeks postoperative. Accompanying cardiac hypertrophy at these postoperative times, there was a decrease in both tissue PO2 levels and cAMP concentrations in the hemodynamically stressed ventricle, the right ventricle. Myosin ATPase activity was elevated as well as the velocity of contractile element shortening. The hemodynamically nonstressed left ventricle did not hypertrophy at these early postoperative times.
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PMID:Changes in cAMP concentrations during chronic cardiac hypertrophy. 21 47

Proteins of apparent molecular weights between 10 000 and 250 000 could be solubilized from guinea pig epidermis using a Tris/sucrose/ATP buffer. When the ionic concentration of the solubilized extract was made 75 mM with respect to KCl and 2 mM with respect to MgCl2, a protein complex precipitated which on SDS-polyacrylamide gel electrophoresis resolved into bands corresponding in migration to myosin, actin and a number of low molecular weight proteins. Myosin was dissociated from the complex with 0.6 M KI and purified by gel filtration chromatography on an agarose column. The purified epidermal myosin fraction contained a polypeptide of 200 000 molecular weight andtwo low molecular weight polypeptides of 16 500 and 13 000. The amino acid composition of the epidermal myosin heavy chain was similar to that of muscle myosin. At high ionic strength epidermal myosin had high specific (K+ + Ca2+)- and (K+ + EDTA)-ATPase activities and low specific (K+ + Mg2+)-ATPase activity. The pH activity curves of the (K+ + Ca2+)- and (K+ + EDTA)-ATPase were different. ATP was hydrolyzed faster than other nucleoside triphosphates. At low ionic strength, the (K+ + Mg2+)-ATPase activity of epidermal myosin was stimulated two fold by skeletal muscle actin. The myosin formed bipolar filaments in 50 mM KCl in the presence of 5 mM Mg2+.
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PMID:Contractile proteins in epidermis. Isolation and properties of guinea-pig epidermal myosin. 22 13

Young rats treated with 10 to 14 daily injections of 2,4-dichlorophenoxyacetate (2,4-D) developed a myopathy mainly involving fast muscles. Myosin isolated from the gastrocnemius muscles of treated and normal control animals differed in several respects. The Ca2+- and Mg2+-mediated ATPases were higher in myopathic muscle myosin than in normals. Alkylation of thiols by N-ethylmaleimide (NEM) induced an increase of Ca2+-activated ATPase that was higher in normal than in myopathic myosin. Trinitrophenylation of reactive amino groups by 2,4,6-trinitrobenzene sulfonate (TBS) induced on increase in Mg2+-mediated ATPase in both preparations, but the increase was higher in normals. Although the heavy- and light-chain pattern was identical in normal and myopathic myosin, during storage at 0 degrees C the relative amount of myopathic L2 light chain decreased. Myosins fragmented either by limited proteolysis with trypsin and chymotrypsin or by specific cleavage at tryptophanyl and cysteinyl peptide bonds showed differences on sodium dodecylsulfate (SDS)-polyacrylamide-gel electrophoresis. The results indicate that there is a change in the heavy chains of myosin isolated from the gastrocnemius muscle in 2,4-D-induced rat myopathy.
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PMID:Myosin changes in experimental 2,4-dichlorophenoxyacetate myopathy. 23 48

Actomyosin was extracted from smooth muscle of molluscan abalone with 0.1 M PPit pH 6.4. Myosin was separated from the actomyosin by centrifugation at 100,000 X g in the presence of 5 mM ATP and 10 mM MgCl2. Myosin in the supernatant was further purified by gel filtration on a Sepharose 4B column. Paramyosin contamination of the actomyosin preparation interfered with the isolation of myosin and complete removal of actin and paramyosin from the myosin has not been accomplished. The myosin appeared to consist of a single f-chain and a single g-chain, as examined by SDS-disc electrophoresis in 8 or 13.7% acrylamide gel. The ATPase [EC 3.6.1.3] activity of this myosin in 0.5 M KCL at neutral pH and at 0 degrees was rather unstable and decreased by 10-20% per day. The effects of rho-chloromercuribenzoate and EDTA on the ATPase activity were similar to those observed with other smooth muscle myosin but the dependence upon pH or KCL concentration was different.
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PMID:Myosin from molluscan abalone, Haliotis discus. Isolation and enzymatic properties. 23 37

Muscle biopsy samples were obtained from healthy subjects in order to evaluate quantitative differences in single fibres of substrate (glycogen and triglyceride) and ion concentrations (Na+ and K+) as well as enzyme activity levels (succinate-dehydrogenase, SDH; phosphofructokinase, PFK; 3-hydroxyacyl-CoA-dehydrogenase, HAD; myosin ATPase) between human skeletal muscle fibre types. After freeze drying of the muscle specimen fragments of single fibres were dissected out and stained for myofibrillar-ATPase with preincubations at pH's of 10.3, 4.6, 4.35. Type I ("red") and II A,B, and C ("white") fibres could then be identified. Glycogen content was the same in different fibres, whereas triglyceride content was highest in Type I fibres (2-3 X Type II). No significant differences were observed for Na+ and K+ between fibre types. The activity for the enzymes studied were quite different in the fibre types (SDH and HAD, Type I is approximately 1.5 X Type II; PFK Type I is approximately 0.5 X Type II, Myosin ATPase Type I is approxiamtely 0.4 X Type II). The subgroups of Type II fibres were distinguished by differences in both SDH and PFK activities (SDH, Type II C is greater than A is greater than B; PFK, Type II B is greater than A is approximately C). It is concluded that contractile and metabolic characteristics of human skeletal fibres are very similar to many other species. One difference, however, appears to be than no Type II fibres have an oxidative potential higher than Type I fibres.
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PMID:Metabolic characteristics of fibre types in human skeletal muscle. 24 87

1. Myosin from the thin-filament regulated flexor muscle of lobster contains 2 moles of each of 2 light chains. 2. The Lb 1 light chain of 19,000 daltons which can be removed by DTNB is heavier than the DTNB light chain of chicken. The Lb 2 light chain of 17,000 daltons can be removed with urea. 3. On electrophoresis in 8 M urea (pH 8.7) the Lb 2 light chain migrates with a mobility similar to that of chicken A2, but the Lb 1 migrates significantly faster than any of the chicken light chains. 4. In lobster, the DTNB treatment destroys the Ca and K-EDTA ATPase activity of lobster myosin.
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PMID:Lobster (Homarus americanus) striated muscle myosin. 31 40

1) The contractile system consists of thick and thin filaments arranged side by side in a double network of hexagonal cross-section. 2) The thick filaments are principally made up of myosin and the thin ones of actin, tropomyosin and troponin. 3) Myosin is an enzyme catalysing the hydrolysis of ATP; actin increases the specific activity of this enzyme, converting it from a Ca+2 sensitive ATPase to a Mg+2 sensitive ATPase. 4) Hydrolysis of the last phosphoryl group of adenosine triphosphate (ATP) salts is the energy source for muscle contraction. 5) The adenosine diphosphate (ADP) salts, formed by ATP splitting, are rephosphorylated and reinjected into the myofibril.
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PMID:Ultrastructure of the contractile system of striated skeletal muscle and the processes of muscular contraction. I. Ultrastructure of the myofibril and source of energy. 76 91

1. Changes of structural proteins in experimental and human myocardial infarction were studied by the determination of myosin- and actomyosin-ATPase activities and gel electrophoretic analysis in the presence of sodium dodecyl sulfate (SDS). 2. In animal experiments using dogs, the relative amounts of myosin and alpha-actinin decreased at 24 to 48 hours after coronary ligation, became lowest at 72 hours, and remained at this level for 2 weeks and returned to almost normal value at 28 days. 3. Myosin- and actomyosin-ATPase activities decreased rapidly during 24 to 48 hours after ligation with temporary increase in their activities in the initial stage of ischemia and followed the similar time course as that of the amounts of myosin and alpha-actinin. 4. SDS gel electrophoretic analysis of structural proteins of infarcted tissues of the human hearts obtained from 5 cadavers showed also marked decrease of the contents of myosin and alpha-actinin with relative preservation of actin, tropomyosin and troponin-T.
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PMID:Changes of cardiac structural proteins in myocardial infarction. 92 15


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