Dimethyl sulphoxide enhances the effects of P(i) in myofibrils and inhibits the activity of rabbit skeletal muscle contractile proteins
| Autor: | A C, Mariano, G M, Alexandre, L C, Silva, A, Romeiro, L C, Cameron, Y, Chen, P B, Chase, M M, Sorenson |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Ethylene Glycol
Myosin Subfragments macromolecular substances Calcium-Transporting ATPases In Vitro Techniques Myosins Phosphates Kinetics Adenosine Triphosphate Contractile Proteins Myofibrils Isometric Contraction Animals Calcium Dimethyl Sulfoxide Magnesium Ca(2+) Mg(2+)-ATPase Rabbits Muscle Skeletal Chickens Edetic Acid Research Article |
| Zdroj: | The Biochemical journal. 358(Pt 3) |
| ISSN: | 0264-6021 |
| Popis: | 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 P(i) 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-S1 MgATPase 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 Ca(2+) and regulatory proteins, in contrast with the effects of ethylene glycol, and the Ca(2+) sensitivity of isometric tension is slightly decreased by DMSO. The apparent affinity for P(i) 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.P(i) or ATP bound to them. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|