Kinetic studies of the active sites functioning in the quinohemoprotein fructose dehydrogenase

FEBS Lett. 1993 Feb 22;318(1):23-6. doi: 10.1016/0014-5793(93)81319-u.

Abstract

Steady-state kinetic analysis was performed on the reaction between D-fructose and ferricyanide with the quinohemoprotein fructose dehydrogenase from Gluconobacter species. The D-fructose oxidation dependence on the ferricyanide concentration resulted in a series of parallel reciprocal plots, and the reaction was assumed to proceed by a ping-pong type of mechanism. A reciprocal plot of the reduction of ferricyanide at saturating concentration of D-fructose gave a break which was considered to appear as a result of the two active centers, namely PQQ and heme c functioning. A scheme of action is proposed and the bimolecular rate constant of the D-fructose oxidation, the kcat for PQQ and the electron transfer rate between the PQQH2 and heme c are calculated and account for 2.2 +/- 0.4 x 10(4) M-1 s-1, (93 +/- 14) and (162 +/- 7) s-1, respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Carbohydrate Dehydrogenases / metabolism*
  • Electron Transport
  • Ferricyanides / metabolism
  • Fructose / metabolism*
  • Kinetics
  • Oxidation-Reduction

Substances

  • Ferricyanides
  • hexacyanoferrate III
  • Fructose
  • Carbohydrate Dehydrogenases
  • D-fructose 5-dehydrogenase