Time-resolved x-ray diffraction studies of the sarcoplasmic reticulum membrane during active transport.
X-ray and neutron diffraction studies of oriented multilayers of a highly purified fraction of isolated sarcoplasmic reticulum (SR) have previously 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 used biosynthetically deuterated SR phospholipids incorporated isomorphously into the isolated SR membranes via phospholipid transfer proteins. Time-resolved x-ray diffraction studies of these oriented SR membrane multilayers have detected significant changes in the membrane profile structure associated with phosphorylation of the Ca2+-ATPase within a single turnover of the Ca2+-transport cycle. These studies used the flash photolysis of caged ATP to effectively synchronize the ensemble of Ca2+-ATPase molecules in the multilayer, synchrotron x-radiation to provide 100-500-ms data collection times, and double-beam spectrophotometry to monitor the Ca2+-transport process directly in the oriented SR membrane multilayer.
Blasie
J K
JK
Herbette
L G
LG
Pascolini
D
D
Skita
V
V
Pierce
D H
DH
Scarpa
A
A
D000818:Animals; D001693:Biological Transport, Active; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D007700:Kinetics; D009132:Muscles / Q000378:metabolism; D009502:Neutrons; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D013057:Spectrum Analysis; D013997:Time Factors; D014961:X-Ray Diffraction / Q000379:methods
D000252:Calcium-Transporting ATPases