Lipid molecular motion and enzyme activity in sarcoplasmic reticulum membrane.

摘要: In biochemically active sarcoplasmic reticulum vesicles (SR) the physical state of membrane lipids was studied by high angle x-ray diffraction and proton nuclear magnetic resonance (NMR) at 220 MHz, related to thermal effects observed in SR functional parameters. It is shown that even temperatures as low 1 degree C nearly all lipid hydrocarbon chains are a disordered conformation only very small part (less than 3%) rigid crystalline order. Consistent with this observation, NMR data indicate majority phospholipid molecules restricted anisotropic motion having no apparent order 5 degrees C. At temperature most signal contained broad feature-less line 700-Hz half-width. On other hand, raised, high-resolution signals, representing groups highly isotropic motion, begin grow intensity. estimated 35 90-100% phosphatidylcholine N-methyl protons 35% hydrocarbon-chain give signals. Concurrent studies on parameters reveal giving rise nonlinear Arrhenius plots for rates calcium transport activated ATPase. The character molecular exhibit parallel behavior, suggesting relationship between enzyme activity lipids.