title: Fluorescence study on transmembrane Ca2+ gradient-mediated conformation changes of sarcoplasmic reticulum Ca(2+)-ATPase.
abstract: The conformational states of Ca(2+)-ATPase in sarcoplasmic reticulum (SR) vesicles with or without a thousand-fold transmembrane Ca2+ gradient have been studied by fluorescence spectroscopy and fluorescence quenching. In consequence of the establishment of the transmembrane Ca2+ gradient, the steady-state fluorescence results revealed a reproducible 8% decrease in the intrinsic fluorescence while time-resolved fluorescence measurements showed that 13 tryptophan residues in SR.Ca(2+)-ATPase could be divided into three groups. The fluorescence lifetime of one of these groups increased from 5.5 ns to 5.95 ns in the presence of a Ca2+ gradient. Using KI and hypocrellin B (a photosensitive pigment obtained from a parasitic fungus, growing in Yunnan, China), the fluorescence quenching further indicated that the dynamic change of this tryptophan group, located at the protein-lipid interface, is a characteristic of transmembrane Ca2+ gradient-mediated conformational changes in SR.Ca(2+)-ATPase.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China.
authors.forename: Y P
authors.initials: YP
authors.lastname: Tu
authors.forename: F Y
authors.initials: FY
authors.lastname: Yang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000737:chemistry*; D008564:Membrane Potentials; D010569:Perylene / Q000031:analogs & derivatives / Q000378:metabolism; D011487:Protein Conformation; D011809:Quinones / Q000378:metabolism; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
chemical_list: D011809:Quinones; D010569:Perylene; D000252:Calcium-Transporting ATPases; D002118:Calcium; C064522:hypocrellin B