Thymol: a classical small-molecule compound that has a dual effect (potentiating and inhibitory) on myosin.
The effect of thymol on the ATPase activity of myosin subfragment-1 (S1) and on the contractile properties of skinned skeletal muscle fibers was studied. At concentrations of 1.5-2 mM, thymol activated the S1 ATPase substantially and the actin-activated S1 ATPase modestly. At the same concentrations, the isometric force of skinned skeletal muscle fibers was modestly suppressed (11% at 2 mM). However, the kinetic parameters of contraction were suppressed more: the velocity of shortening and the rate of force redevelopment after shortening were suppressed by 43% and 31% at 2 mM, respectively. Thus, among other small-molecule inhibitors, thymol is unique in that it has opposite effects on the enzymatic activity and kinetic parameters of contraction. Thymol may serve as a potent tool for studying the mechanism of coupling between the ATPase reaction and contraction in muscle.
Tamura
Takumi
T
Structural Biochemistry Laboratory, RIKEN Harima Institute, SPring-8, Hyogo 679-5148, Japan.
Iwamoto
Hiroyuki
H
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D003609:Dactinomycin / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D015879:Myosin Subfragments / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D016658:Psoas Muscles / Q000187:drug effects / Q000502:physiology; D011817:Rabbits; D024744:Skeletal Muscle Myosins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D013943:Thymol / Q000494:pharmacology*
D015879:Myosin Subfragments; D003609:Dactinomycin; D013943:Thymol; D017301:Ca(2+) Mg(2+)-ATPase; D024744:Skeletal Muscle Myosins