Modulating the Copper-Sulfur Interaction in Type 1 Blue Copper Azurin by Replacing Cys112 with Nonproteinogenic Homocysteine.

ABSTRACT: The Cu-S_Cys interaction is known to play a dominant role in defining the type 1 (T1) blue copper center with respect to both its electronic structure and electron transfer function. Despite this importance, its role has yet to be probed by mutagenesis studies without dramatic change of its T1 copper character. We herein report replacement of the conserved Cys112 in azurin with the nonproteinogenic amino acid homocysteine. Based on electronic absorption, electron paramagnetic resonance, and extended x-ray absorption fine structural spectroscopic studies, this variant displays typical type 1 copper site features. Surprisingly, instead of increasing the strength of the Cu-sulfur interaction by the introduction of the extra methylene group, the Cys112Hcy azurin showed a decrease in

SUBMITTER: Clark KM 

PROVIDER: S-EPMC3972132 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature