Evidence against proton pump activity by cytochrome c oxidase of Pseudomonas AM1 |
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Authors: | N Sone M Sekimachi Y Fukumori T Yamanaka |
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Institution: | Department of Biochemistry, Jichi Medical School, Tochigi. |
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Abstract: | 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. |
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