Defining the role of the axial ligand of the type 1 copper site in amicyanin by replacement of methionine with leucine.

ABSTRACT: The effects of replacing the axial methionine ligand of the type 1 copper site with leucine on the structure and function of amicyanin have been characterized. The crystal structures of the oxidized and reduced forms of the protein reveal that the copper site is now tricoordinate with no axial ligand, and that the copper coordination distances for the two ligands provided by histidines are significantly increased. Despite these structural changes, the absorption and EPR spectra of M98L amicyanin are only slightly altered and still consistent with that of a typical type 1 site. The oxidation-reduction midpoint potential (E(m)) value becomes 127 mV more positive as a consequence of the M98L mutation, most likely because of the increased hydrophobicity of the copper site. The most dramatic ef

SUBMITTER: Choi M 

PROVIDER: S-EPMC2756040 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature