title: 1,3-Diethylurea-enhanced Mg-ATPase activity of skeletal muscle myosin with a converse effect on the sliding motility.
abstract: We investigate the effects of urea and its derivatives on the ATPase activity and on the in vitro motility of chicken skeletal muscle actomyosin. Mg-ATPase rate of myosin subfragment-1 (S1) is increased by 4-fold by 0.3M 1,3-diethylurea (DEU), but it is unaffected by urea, thiourea, and 1,3-dimethylurea at ≤1M concentration. Thus, we further examine the effects of DEU in comparison to those of urea as reference. In in vitro motility assay, we find that in the presence of 0.3M DEU, the sliding speeds of actin filaments driven by myosin and heavy meromyosin (HMM) are significantly decreased to 1/16 and 1/6.6, respectively, compared with the controls. However, the measurement of the actin-activated ATPase activity of HMM shows that the maximal rate, Vmax, is almost unchanged with DEU. Thus, the myosin-driven sliding motility of actin filaments is significantly impeded in the presence of 0.3M DEU, whereas the cyclic interaction of myosin with F-actin occurs during the ATP turnover, the rate of which is close to that without DEU. In contrast to DEU, 0.3M urea exhibits only modest effects on both actin-activated ATPase and sliding motility of actomyosin. Thus, DEU has the effect of uncoupling the sliding motility of actomyosin from its ATP turnover.
authors: Department of Materials Processing, Graduate School of Engineering, Tohoku University, Aoba-yama 02, Aoba-ku, Sendai 980-8579, Japan.
authors: Tetsuichi
authors: T
authors: Wazawa
authors: Shin-ichiro
authors: S
authors: Yasui
authors: Nobuyuki
authors: N
authors: Morimoto
authors: Makoto
authors: M
authors: Suzuki
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000205:Actomyosin / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D002645:Chickens; D009068:Movement; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism; D024744:Skeletal Muscle Myosins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000199:Actins; D015879:Myosin Subfragments; D000255:Adenosine Triphosphate; D000205:Actomyosin; D024744:Skeletal Muscle Myosins
keywords: ATP hydrolysis; Actomyosin; Alkylurea derivative; Cosolvent effect; Mechanochemical coupling; Sliding motility