Evidence against proton pump activity by cytochrome c oxidase of Pseudomonas AM1.
Proteoliposomes reconstituted from purified cytochrome c oxidase of Pseudomonas AM1 and from a heptyl beta-D-thioglucoside-extract of its membranes showed respiratory control but did not show H+ pumping upon a pulse with reduced cytochrome c. The stoichiometries of respiration-dependent H+ translocation in the resting cells respiring ascorbate via N,N,N',N'-tetramethyl-p-phenylenediamine were measured by the oxygen-pulse and initial rate methods. The apparent H+/O ratio of about 2 was due to 2H+ release from the hydrogen-donating substrate. These results strongly suggested that Pseudomonas AM1 does not pump H+ intrinsically, although the enzyme catalyzes electron transfer across the membranes.
Sone
N
N
Department of Biochemistry, Jichi Medical School, Tochigi.
Sekimachi
M
M
Fukumori
Y
Y
Yamanaka
T
T
D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010101:Oxygen Consumption; D011522:Protons; D011549:Pseudomonas / Q000201:enzymology* / Q000378:metabolism
D011522:Protons; D003576:Electron Transport Complex IV