Dependence of the fluorescence of fluorescein labelled (Ca2+, Mg2+)-ATPase upon the lipid to protein ratio in sarcoplasmic reticulum reconstituted systems.
Reconstituted sarcoplasmic reticulum (SR) vesicles have been prepared mixing fluorescein labelled SR, excess endogenous lipids and deoxycholate by a rapid dilution protocol and several freeze-thaw treatments. We have found that both the steady-state level and the polarization of fluorescein fluorescence of these reconstituted systems monotonically increase as a function of the lipid to protein ratio between 80 and 2000 (on a mole per mole basis). The magnitude of this increase is about 15%. Detergents, such as Triton X-100 and deoxycholate, when added to SR labelled vesicles below their critical micelle concentrations also induce similar changes in fluorescein fluorescence. We suggest that lipid dilution of protein in these reconstituted systems induce a decrease of the level of self-quenching by promoting dissociation of (Ca2+, Mg2+)-ATPase.
Mata
A M
AM
Gutiérrez-Merino
C
C
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000032:analysis*; D000252:Calcium-Transporting ATPases / Q000032:analysis*; D005452:Fluoresceins; D005453:Fluorescence; D066298:In Vitro Techniques; D008055:Lipids / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000032:analysis / Q000201:enzymology*
D005452:Fluoresceins; D008055:Lipids; D011506:Proteins; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases