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Kinetic studies of the active sites functioning in the quinohemoprotein fructose dehydrogenase
Author(s) -
Marcinkeviciene Jovita,
Johansson Gillis
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81319-u
Subject(s) - ferricyanide , chemistry , fructose , electron transfer , reaction rate constant , dehydrogenase , marcus theory , redox , photochemistry , stereochemistry , kinetics , inorganic chemistry , organic chemistry , enzyme , physics , quantum mechanics
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 e functioning. A scheme of action is proposed and the bimolecular rate constant of the d ‐fructose oxidation, the k cat for PQQ and the electron transfer rate between the PQQH 2 and heme c are calculated and account for 2.2 ± 0.4.10 4 M −1 s −1 , (93 ± 14) and (162 ± 7) s −1 , respectively.