Phosphoenzyme conversion of the sarcoplasmic reticulum Ca(2+)-ATPase: molecular interpretation of infrared difference spectra

  • Time-resolved Fourier transform infrared difference spectra of the phosphoenzyme conversion and Ca(2+) release reaction (Ca(2)E(1)-P --> E(2)-P) of the sarcoplasmic reticulum Ca(2+)-ATPase were recorded at pH 7 and 1 degrees C in H(2)O and (2)H(2)O. In the amide I spectral region, the spectra indicate backbone conformational changes preserving conformational changes of the preceding phosphorylation step. beta-sheet or turn structures (band at 1685 cm(-1)) and alpha-helical structures (band at 1653 cm(-1)) seem to be involved. Spectra of the model compound EDTA for Ca(2+) chelation indicate the assignment of bands at 1570, 1554, 1411 and 1399 cm(-1) to Ca(2+) chelating Asp and Glu carboxylate groups partially shielded from the aqueous environment. In addition, an E(2)-P band at 1638 cm(-1) has been tentatively assigned to a carboxylate group in a special environment. A Tyr residue seems to be involved in the reaction (band at 1517 cm(-1) in H(2)O and 1515 cm(-1) in (2)H(2)O). A band at 1192 cm(-1) was shown by isotopic replacement in the gamma-phosphate of ATP to originate from the E(2)-P phosphate group. This is a clear indication that the immediate environment of the phosphoenzyme phosphate group changes in the conversion reaction, altering phosphate geometry and/or electron distribution.

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Metadaten
Author:Andreas BarthORCiD
URN:urn:nbn:de:hebis:30:3-758658
DOI:https://doi.org/10.1074/jbc.274.32.22170
ISSN:0021-9258
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/10428781
Parent Title (English):Journal of biological chemistry
Publisher:American Society for Biochemistry and Molecular Biology Publications
Place of publication:Bethesda, Md
Document Type:Article
Language:English
Date of Publication (online):2021/01/04
Year of first Publication:1999
Publishing Institution:Universit├Ątsbibliothek Johann Christian Senckenberg
Release Date:2023/09/21
Volume:274
Issue:32
Page Number:6
First Page:22170
Last Page:22175
HeBIS-PPN:513164421
Institutes:Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Sammlungen:Universit├Ątspublikationen
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International