Kinetic characterization of Desulfovibrio gigas hydrogenase upon selective chemical modification of amino acid groups as a tool for structure-function relationships.
The effect of amino acid residues modification of Desulfovibrio gigas hydrogenase on different activity assays is reported. The first method consisted in the modification of glutamic and aspartic acid residues of the enzyme with ethylenediamine in order to change the polarity of certain regions of the protein surface. The second method consisted in the modification of histidine residues with a Ru complex in order to change the acid-base properties of the histidine residues. The implication of these modifications in the enzyme kinetics has been studied by measuring in parallel the activities of para/ortho hydrogen conversion, deuterium/hydrogen exchange and dyes reduction with hydrogen. Our experimental data support some hypothesis based on the three-dimensional structure of this enzyme: (a) electrostactic interactions between the hydrogenase and the redox partner play an essential role in the kinetics; (b) the histidine ligand and the surrounding acidic residues of the distal [4Fe4S] cluster form the recognition site of the redox partner of the hydrogenase; and (c) histidine residues are involved in the hydron transfer pathway of the hydrogenase.
De Lacey
A L
AL
Instituto de Catálisis, C.S.I.C., Campus Universidad Autónoma-Cantoblanco, Madrid, Spain. alopez@icp.csic.es
Santamaria
E
E
Hatchikian
E C
EC
Fernandez
V M
VM
D000596:Amino Acids / Q000737:chemistry; D003901:Desulfovibrio / Q000201:enzymology*; D004579:Electron Transport; D005029:Ethylenediamines / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D010084:Oxidation-Reduction; D010269:Paraquat / Q000737:chemistry; D055672:Static Electricity; D013329:Structure-Activity Relationship
D000596:Amino Acids; D005029:Ethylenediamines; D006639:Histidine; C031234:ethylenediamine; D006864:Hydrogenase; D010269:Paraquat