Redox Potentials of Certain Vitamins K: Implications for a Role in Sulfite Reduction by Obligately Anaerobic Bacteria

  1. G. C. Wagner,
  2. R. J. Kassner, and
  3. M. D. Kamen
  1. Department of Chemistry, University of Illinois at Chicago Circle, Chicago, Ill. 60680
  2. Department of Chemistry, University of California at San Diego, La Jolla, Calif. 92037

Abstract

Redox potentials of a menaquinone (MK-6), isolated in earlier researches from two species of the obligately anaerobic genus, Desulfovibrio, as well as two other vitamins K2—menaquinones (MK-5) and (MK-9)— have been determined polarographically. The measurements have been validated by determination of redox potentials of 1,4-naphthoquinone and vitamin K1 which agree with published potentiometric values. Em7 for menaquinone (MK-6) is -0.067 ± 0.010 V. Redox potentials calculated for terminal acceptor couples currently proposed in the mechanisms of sulfate reduction by Desulfovibrio are consistent with the involvement of menaquinone (MK-6) in at least one of the steps postulated during electron transfer with ultimate production of sulfide.

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  1. PNAS 1974-02 vol. 71 no. 2 253-256
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