The activation of the [NiFe]-hydrogenase from Allochromatium vinosum. An infrared spectro-electrochemical study.
The membrane-bound [NiFe]-hydrogenase from Allochromatium vinosum can occur in several inactive or active states. This study presents the first systematic infrared characterisation of the A. vinosum enzyme, with emphasis on the spectro-electrochemical properties of the inactive/active transition. This transition involves an energy barrier, which can be overcome at elevated temperatures. The reduced Ready enzyme can exist in two different inactive states, which are in an apparent acid-base equilibrium. It is proposed that a hydroxyl ligand in a bridging position in the Ni-Fe site is protonated and that the formed water molecule is subsequently removed. This enables the active site to bind hydrogen in a bridging position, allowing the formation of the fully active state of the enzyme. It is further shown that the active site in enzyme reduced by 1 bar H(2) can occur in three different electron paramagnetic resonance (EPR)-silent states with a different degree of protonation.
Bleijlevens
Boris
B
Swammerdam Institute for Life Sciences, Biochemistry, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands.
van Broekhuizen
Fleur A
FA
De Lacey
Antonio L
AL
Roseboom
Winfried
W
Fernandez
Victor M
VM
Albracht
Simon P J
SP
D002841:Chromatiaceae / Q000201:enzymology*; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D009532:Nickel / Q000737:chemistry / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared
D009532:Nickel; D007501:Iron; C043296:nickel-iron hydrogenase; D006864:Hydrogenase