title: Static and time-resolved structural studies of the Ca2+-ATPase of isolated sarcoplasmic reticulum.
abstract: X-ray and neutron diffraction studies of oriented multilayers of isolated light sarcoplasmic reticulum (SR) have provided the separate profile structures of the lipid bilayer and the Ca2+-ATPase molecule within the membrane profile to approximately 10 A resolution. These studies utilized biosynthetically deuterated SR phospholipids incorporated isomorphously into the isolated SR membranes via exchange proteins. Time-resolved x-ray diffraction studies of these oriented SR membrane multilayers have indicated that significant changes occur in the membrane profile structure within a single turnover of the Ca2+-transport cycle. These studies utilized the flash photolysis of caged ATP to effectively synchronize the ensemble of Ca2+-ATPase molecules in the multilayer, synchrotron x-radiation to provide 100- to 500-millisecond data collection times, and double-beam spectrophotometry to monitor Ca2+ transport in the oriented SR membrane multilayer.
mesh_terms: D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D007700:Kinetics; D008051:Lipid Bilayers; D008563:Membrane Lipids / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D008051:Lipid Bilayers; D008563:Membrane Lipids; D000252:Calcium-Transporting ATPases