The Ca2+sensitivity of the actin‐activated ATPase of scallop heavy meromyosin

FEBS Letters

Wells, Christine¹  Bagshaw, Clive R.¹ 

[1] Department of Biochemistry, University of Leicester, Leicester LE1 7RH, England

关键词: Kinetics;    ATPase;    Heavy meromyosin;    Myosin-linked regulation;    CA2+ activation;    HMM;    heavy meromyosin;    Tes;    N-tris-hydroxymethyl)methyl-2-aminoethanesulphonic acid;   

DOI  :  10.1016/0014-5793(84)80258-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The actin-activated scallop heavy meromyosin (HMM) ATPase was monitored turbidometrically during a limited number of turnovers. At 4 μM actin, the turnover rate in the presence of Ca²⁺ (1.2 s⁻¹ per head) was 650-fold higher than in its absence (1.8 × 10⁻³ s⁻¹), a Ca²⁺ sensitivity which approaches that expected in vivo. The extent of Ca²⁺ activation was much larger than the observed by steady-state measurements, where the rate, in the absence of Ca²⁺, is dominated by a small proportion of unregulated molecules. Acto-HMM formation, and its dissociation by ATP, were Ca²⁺ insensitive.

【 授权许可】

Unknown