Roles of long-range electrostatic domain interactions and K+ in phosphoenzyme transition of Ca2+-ATPase.

ABSTRACT: Sarcoplasmic reticulum Ca(2+)-ATPase couples the motions and rearrangements of three cytoplasmic domains (A, P, and N) with Ca(2+) transport. We explored the role of electrostatic force in the domain dynamics in a rate-limiting phosphoenzyme (EP) transition by a systematic approach combining electrostatic screening with salts, computer analysis of electric fields in crystal structures, and mutations. Low KCl concentration activated and increasing salt above 0.1 m inhibited the EP transition. A plot of the logarithm of the transition rate versus the square of the mean activity coefficient of the protein gave a linear relationship allowing division of the activation energy into an electrostatic component and a non-electrostatic component in which the screenable electrostatic forces are shiel

SUBMITTER: Yamasaki K 

PROVIDER: S-EPMC3711328 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature