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Updated: Jan 4, 2026
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Published on: April 5, 2022
pH-Induced Binding of the Axial Ligand in an Engineered CuA Site Favors the πu State
Marcos N Morgada1, Florencia Emiliani1, Kelly N Chacón2
1Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Ocampo y Esmeralda, Predio CONICET Rosario, 2000 Rosario , Argentina.
Abstract:
CuA centers perform efficient long-range electron transfer. The electronic structure of native CuA sites can be described by a double-potential well with a dominant σu* ground state in fast equilibrium with a less populated πu ground state. Here, we report a CuA mutant in which a lysine was introduced in the axial position. This results in a highly unstable protein with a pH-dependent population of the two ground states. Deep analysis of the high-pH form of this variant shows the stabilization of the πu ground state due to direct binding of the Lys residue to the copper center that we attribute to deprotonation of this residue.
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