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Protonation of the Copper(I) Form of the Blue Copper Proteins Plastocyanin and Amicyanin – A Molecular Dynamics Study
Author(s) -
Buning Christian,
Comba Peter
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(200006)2000:6<1267::aid-ejic1267>3.0.co;2-t
Subject(s) - plastocyanin , protonation , chemistry , conformational isomerism , copper , copper protein , crystallography , histidine , computational chemistry , molecule , amino acid , organic chemistry , photosystem i , biochemistry , photosynthesis , photosystem ii , ion
The conformational space of the copper(I) forms of the cupredoxines amicyanin (ami) ( Paracoccus versutus ) and plastocyanin (pla) ( Populus nigra ) with a protonated histidine donor close to the C‐terminus (“C‐terminal histidine” ami: His96; pla: His87) was investigated with force field calculations that involve the experimentally determined structures of the protonated or unprotonated copper(I/II) forms: a setup of 36 conformers with a constrained torsional angle that involves the C imidazole –C methylene (C γ –C β ) bond (chi2; 10° increments); strain energy minimization of all constrained conformers; a 10 ps molecular dynamics search around each conformer; constrained, followed by unconstrained optimization of each of the resulting low energy structures; cluster analysis of the resulting conformations. For both cupredoxines there are two major conformers which differ in their solvent accessibility. The plastocyanin and amicyanin structures are in excellent agreement with the experimentally observed crystallographic data; the two analyses lead to the proposal for a general mechanism for the protonation of reduced blue copper proteins. This is also in agreement with the results of a conformational analysis of a complex of the protonated copper(I) form of amicyanin with phosphate.