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 this study we examined the effects of 3-24 h of incubation of chemically skinned rat fast-twitch muscle with the glycolytic metabolite glucose 6-phosphate (G6-P) on the contractile properties and myosin ATPase activity in single muscle fibres, and on the carbohydrate content of myosin heavy chains (MHCs). Exposure of the permeabilised muscle to 10 mM G6-P for 24 h at 22+/-1 degrees C in a rigor solution containing protease inhibitors and a reducing agent (dithiothreitol, DTT) significantly decreased maximum Ca(2+)-activated force output by 31%, lowered the Ca2+ threshold for contraction by 0.1 pCa units and produced shallower force-pCa curves compared with controls. Furthermore, under these conditions, G6-P-treated muscle displayed lower myofibrillar MgATPase activity and a markedly higher carbohydrate content of MHCs, as identified with an immunoblot protocol for glycoprotein detection. Shorter incubations under the same conditions or 24-h incubations with 5 mM G6-P generally resulted in smaller changes in the contractile activation parameters. These findings suggest that reducing sugars acting as metabolic intermediates in the glycolytic pathway can have important non-energy-related effects on the contractile activation characteristics of mammalian skeletal muscle. These effects are consistent with the glycation of muscle proteins, in particular that of the MHC.
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PMID:Ca2+-activation characteristics of single fibres from chemically skinned rat muscle incubated with glucose-6-phosphate. 1078 61

Mercury reduces twitch and tetanic force development in isolated rat papillary muscles, and a putative toxic effect on the contractile machinery has been suggested. Based on that, the actions of HgCl2 on the myosin ATPase activity of the left ventricular myocardium were investigated. Samples for assay of myosin ATPase activity were obtained from rats' left ventricles. Increasing concentrations of HgCl2 reduced dose-dependently the activity of the myosin ATPase. This reduction was observed even at very small concentrations, 50 nM HgCl2. This effect was dependent on the presence of SH groups in the myosin molecule since DTT and glutathione protected the myosin ATPase against toxic effects of mercury; full activity being restored by using 500 nM DTT or 500 nM glutathione. Results also suggested that the metal acts as an uncompetitive inhibitor with a Ki of 200 nM HgCl2. Our results suggest that mercury reduces the activity of the myosin ATPase by an uncompetitive mechanism at a very low dose that does not depress force. DTT and glutathione are effective for protection against the actions of mercury suggesting that SH groups might be the sites of action of the metal on the myosin molecule.
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PMID:Effects of mercury on myosin ATPase in the ventricular myocardium of the rat. 1292 1

The nuclear matrix (NM) of somatic cells is an internal nuclear framework structure, with a structural function and participation in DNA replication and transcription. The NM has been described in mouse, hamster and human spermatozoa. In this study, an NM structural component of the guinea pig sperm nucleus was obtained by removing nuclear proteins and DNA from DTT-CTAB nuclei. Removal was achieved with high ionic strength salt and microccocal nuclease treatments including a heparin treatment to cause a slight swelling of the nucleus and facilitate material extraction. Actin, myosin, cytokeratins and spectrin were detected associated to NM by indirect immunofluorescence, immunogold staining and Western blotting analysis using specific antibodies. The presence of NM in guinea pig sperm nucleus is shown for the first time and some of its components are identified. This is also the first report on cytokeratins and myosin presence in guinea pig sperm. A retarding effect of nuclear decondensation caused by heparin is induced after phalloidin and/or diacetyl-monoxime (a myosin ATPase activity inhibitor) treatment, suggesting a role for F-actin and myosin in the maintenance of nuclear stability in sperm. The actin role was supported by the decondensing effect that citochalasin D and gelsolin had on sperm nuclei.
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PMID:Actin, myosin, cytokeratins and spectrin are components of the guinea pig sperm nuclear matrix. 1597 58