Effects of a Ca2+ gradient and water activity on the phosphorylation of Ca2+‐ATPase by Pi

FEBS Letters

Caldeira, Maria Teresa¹  de Meis, Leopoldo¹ 

[1]Instituto de Ciências Biomêdicas, Departamento de Bioquimica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21910, Brazil

关键词: Phosphorylation by Pi;    Magnesium ion;    Dimethyl sulfoxide;    Sarcoplasmic reticulum;    Ca2+ gradient;   

DOI  :  10.1016/0014-5793(91)80990-K

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The effects of dimethyl sulfoxide (20% v/v) on the phosphorylation of Ca²⁺-ATPase of the sarcoplasmic reticulum by P_i vary depending on whether or not a Ca²⁺ gradient is formed across the vesicle membranes. In the absence of a Ca²⁺ gradient the solvent promotes a large increase in the affinity for P_i. This increase is no longer observed after the formation of a Ca²⁺ gradient. The enzyme affinity for Mg²⁺ is practically the same in the presence and absence of a gradient. Addition of dimethyl sulfoxide leads to an increase of the enzyme affinity for Mg²⁺ both in the presence and in the absence of a gradient.

【 授权许可】

Unknown