ISSN:
0091-7419
Keywords:
(H++K+)-ATPase
;
transport ATPase
;
proton transport
;
phospholipids
;
phospholipase A2
;
CD spectrum
;
gastric ATPase
;
Life Sciences
;
Molecular Cell Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
The phospholipid and fatty acid composition and role of phospholipids in enzyme and transport function of gastric (H++K+)-ATPase vesicles was studied using phospholipase A2 (bee venom). The composition (%) was phosphatidylcholine (PC) 33%; sphingomyelin (sph) 25%; phosphatidylethanolamine (PE) 22%; phosphatidylserine (PS) 11%; and phosphatidylinositol (PI) 8%. The fatty acid composition showed a high degree of unsaturation. In both fresh and lyophilized preparations, even with prolonged incubation, only 50% of phospholipids were hydrolyzed, but the amount of PE and PS disappearing was increased following lyophilization. There was a marked decrease in K+-ATPase activity (75%) but essentially no loss of the associated K+ p-nitrophenyl phosphatase was found. ATPase activity could be largely restored by various phospholipids (PE 〉 PC 〉 PS). There was also an increase in Mg2+-ATPase activity, partially reversed in fresh preparations by the addition of phospholipids (PE 〉 PS 〉 PC). Proton transport activity of the preparation was rapidly inhibited, initially due to a large increase in the HC1 permeability of the preparation. Associated with these enzymatic and functional changes, the ATP-induced conformational changes, as indicated by circular dichroism spectra were inhibited.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jss.400110402
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