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FTIR studies on the bond properties of the aspartyl phosphate moiety of the Ca 2+ –ATPase
Author(s) -
Andersson Julia,
Barth Andreas
Publication year - 2006
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20436
Subject(s) - chemistry , moiety , phosphate , fourier transform infrared spectroscopy , atpase , stereochemistry , crystallography , computational chemistry , enzyme , organic chemistry , chemical engineering , engineering
As part of our work to determine the bond properties of the aspartyl phosphate moiety of the Ca 2+ –ATPase (SERCA1a) phosphoenzymes, we analyzed Morse potentials of the bridging PO bond as well as CO bond strengths for the model compound acetyl phosphate and the two phosphoenzyme intermediates Ca 2 E1P and E2P. Reaction‐induced infrared difference spectroscopy was used and a carbonyl band of E2P at 1708 cm –1 in the presence of m M Mg 2+ was tentatively assigned to the carbonyl group of phosphorylated Asp 351 because of its sensitivity to divalent cations. This band is found at 1716 cm –1 with m M Ca 2+ , for Ca 2 E1P at 1717 cm –1 with Mg 2+ , and at 1719 cm –1 with Ca 2+ and at 1718 cm –1 for acetyl phosphate in the absence of divalent cations. The similar band positions indicate similar strengths of interaction of the carbonyl oxygen in acetyl phosphate and the two phosphoenzymes. Together with information on the PO bond strengths, this implies that the bridging oxygen exerts stronger interactions in the phosphoenzymes than in acetyl phosphate. © 2005 Wiley Periodicals, Inc. Biopolymers 82: 353–357, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com