Structural dynamics of the Ca²⁺-ATPase studied by time-resolved infrared spectroscopy

Issue title: XII European Conference on the Spectroscopy of Biological Molecules, Bobigny, France, 1–6 September 2007, Part 1

Article type: Research Article

Authors: Barth, Andreas

Affiliations: Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden. Tel.: +46 8 162452; Fax: +46 8 155597; E-mail: Andreas.Barth@dbb.su.se

Abstract: This review discusses the contribution of time-resolved infrared spectroscopy to the understanding of the Ca2+ pump in the sarcoplasmic reticulum membrane of skeletal muscle cells (SERCA1a). The focus is on interactions of the substrate ATP with the ATPase and on the bond parameters of the phosphoenzyme phosphate group. Functional groups throughout the ATP molecule are important for stabilising the closed conformation of the ATP–ATPase complex and for fast phosphorylation of the ATPase. Dissociation of the reaction product ADP after phosphorylation leads to a more open average conformation of the enzyme and does not trigger the transition from the first phosphoenzyme Ca2E1P to the second E2P. The P–O bond between phosphate and aspartyl moieties is weaker in Ca2E1P and E2P than in acetyl phosphate in aqueous solution, which explains the high reactivity of the phosphoenzymes. This ground state property of the phosphoenzymes prepares for a phosphate transfer reaction with dissociative character.

Keywords: FTIR, SERCA, Ca^2+ pump, structure, function

DOI: 10.3233/SPE-2008-0342

Journal: Spectroscopy, vol. 22, no. 2-3, pp. 63-82, 2008