دورية
Dimethyl sulphoxide enhances the effects of Pi in myofibrils and inhibits the activity of rabbit skeletal muscle contractile proteins
| العنوان: | Dimethyl sulphoxide enhances the effects of Pi in myofibrils and inhibits the activity of rabbit skeletal muscle contractile proteins |
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| المؤلفون: | MARIANO, Ana C., ALEXANDRE, Giani M. C., SILVA, Leonardo C., ROMEIRO, Alexandre, CAMERON, Luiz Claudio, CHEN, Ying, CHASE, P. Bryant, SORENSON, Martha M. |
| المصدر: | Biochemical Journal; September 2001, Vol. 358 Issue: 3 p627-636, 10p |
| مستخلص: | In the catalytic cycle of skeletal muscle, myosin alternates between strongly and weakly bound cross-bridges, with the latter contributing little to sustained tension. Here we describe the action of DMSO, an organic solvent that appears to increase the population of weakly bound cross-bridges that accumulate after the binding of ATP, but before Pi release. DMSO (5–30%, v/v) reversibly inhibits tension and ATP hydrolysis in vertebrate skeletal muscle myofibrils, and decreases the speed of unregulated F-actin in an in vitro motility assay with heavy meromyosin. In solution, controls for enzyme activity and intrinsic tryptophan fluorescence of myosin subfragment 1 (S1) in the presence of different cations indicate that structural changes attributable to DMSO are small and reversible, and do not involve unfolding. Since DMSO depresses S1 and acto–S1MgATPase activities in the same proportions, without altering acto–S1 affinity, the principal DMSO target apparently lies within the catalytic cycle rather than with actin–myosin binding. Inhibition by DMSO in myofibrils is the same in the presence or the absence of Ca2+ and regulatory proteins, in contrast with the effects of ethylene glycol, and the Ca2+ sensitivity of isometric tension is slightly decreased by DMSO. The apparent affinity for Pi is enhanced markedly by DMSO (and to a lesser extent by ethylene glycol) in skinned fibres, suggesting that DMSO stabilizes cross-bridges that have ADP·Pi or ATP bound to them. |
| قاعدة البيانات: | Supplemental Index |
| تدمد: | 02646021 14708728 |
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| DOI: | 10.1042/bj3580627 |