Incorporation of mitochondrial L-glycerol-3-phosphate dehydrogenase into liposomes; effect of sodium oleate and calcium ions.
FAD-linked L-glycerol-3-phosphate dehydrogenase purified from liver mitochondria of hyperthyroid rats was incorporated into unilamellar phospholipid liposomes. The incorporation influenced both Vmax,app and Km,app values of the enzyme for its substrate, L-glycerol 3-phosphate. The Km,app for the electron acceptor remained unchanged with a simultaneous slight enhancement of the corresponding Vmax,app value. The steady-state fluorescence anisotropies of the fluorescein isothiocyanate and trimethylammoniumdiphenylhexatriene labels were affected by sodium oleate and calcium ions in the case of both solubilized and liposome-incorporated L-glycerol-3-phosphate dehydrogenase. These results indicate that calcium ions cause a significant alteration of the enzyme conformation. Sodium oleate (used as a model of free fatty acids), besides its direct action on the enzyme itself, affects the enzyme indirectly as well, via alteration of the physical properties of the membrane.
Beleznai
Z
Z
Institute of Enzymology, Hungarian Academy of Sciences, Budapest.
Amler
E
E
Jancsik
V
V
Rauchová
H
H
Drahota
Z
Z
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002308:Cardiolipins / Q000032:analysis / Q000494:pharmacology; D004161:Diphenylhexatriene / Q000031:analogs & derivatives; D016650:Fluorescein-5-isothiocyanate; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism*; D005994:Glycerophosphates / Q000378:metabolism; D006980:Hyperthyroidism / Q000201:enzymology; D007700:Kinetics; D008081:Liposomes / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology*; D010743:Phospholipids / Q000032:analysis; D011487:Protein Conformation / Q000187:drug effects; D051381:Rats; D013050:Spectrometry, Fluorescence; D013861:Thiocyanates
D002308:Cardiolipins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005994:Glycerophosphates; D008081:Liposomes; D009829:Oleic Acids; D010743:Phospholipids; D013861:Thiocyanates; D004161:Diphenylhexatriene; D019301:Oleic Acid; C013173:osteum; C033628:1-(4-(trimethylamino)phenyl)-6-phenylhexa-1,3,5-triene; C029620:alpha-glycerophosphoric acid; D005993:Glycerolphosphate Dehydrogenase; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium