Transport ratios of reconstituted (H+ + K+)-ATPase.
Gastric (H+ + K+)-ATPase was reconstituted into artificial phosphatidylcholine/cholesterol vesicles by means of a freeze-thaw-sonication procedure. The passive and active transport mediated by these vesicles were measured (Skrabanja, A.T.P., Asty, P., Soumarmon, A., De Pont, J.J.H.H.M. and Lewin, M.J.M. (1986) Biochim. Biophys. Acta 860, 131-136). To determine real initial velocities, the proteoliposomes were separated from non-incorporated enzyme, by means of centrifugation on a sucrose gradient. The purified proteoliposomes were used to measure active H+ and Rb+ transport, giving at room-temperature velocities of 46.3 and 42.5 mumol per mg per h, respectively. A transport ratio of two cations per ATP hydrolyzed was also measured. These figures indicate that the enzyme catalyzes an electroneutral H+-Rb+ exchange.
Skrabanja
A T
AT
Department of Biochemistry, University of Nijmegen, The Netherlands.
van der Hijden
H T
HT
De Pont
J J
JJ
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002499:Centrifugation, Density Gradient; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D005753:Gastric Mucosa / Q000201:enzymology*; D017506:H(+)-K(+)-Exchanging ATPase; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000378:metabolism*; D011522:Protons; D012413:Rubidium / Q000378:metabolism; D013552:Swine; D014638:Vanadates / Q000494:pharmacology
D002793:Cholic Acids; D008081:Liposomes; D011522:Protons; D014638:Vanadates; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase; D019826:Cholic Acid; D012413:Rubidium