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Effect of circular permutation on the structure and function of type 1 blue copper center in azurin
Author(s) -
Yu Yang,
Petrik Igor D.,
Chacón Kelly N.,
Hosseinzadeh Parisa,
Chen Honghui,
Blackburn Ninian J.,
Lu Yi
Publication year - 2017
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.3071
Subject(s) - azurin , chemistry , copper protein , crystallography , coordination sphere , electron transfer , copper , protein secondary structure , electron paramagnetic resonance , active site , photosynthetic reaction centre , stereochemistry , photochemistry , crystal structure , enzyme , biochemistry , physics , nuclear magnetic resonance , organic chemistry
Abstract Type 1 copper (T1Cu) proteins are electron transfer (ET) proteins involved in many important biological processes. While the effects of changing primary and secondary coordination spheres in the T1Cu ET function have been extensively studied, few report has explored the effect of the overall protein structural perturbation on active site configuration or reduction potential of the protein, even though the protein scaffold has been proposed to play a critical role in enforcing the entatic or “rack‐induced” state for ET functions. We herein report circular permutation of azurin by linking the N‐ and C‐termini and creating new termini in the loops between 1 st and 2 nd β strands or between 3 rd and 4 th β strands. Characterization by electronic absorption, electron paramagnetic spectroscopies, as well as crystallography and cyclic voltammetry revealed that, while the overall structure and the primary coordination sphere of the circular permutated azurins remain the same as those of native azurin, their reduction potentials increased by 18 and 124 mV over that of WTAz. Such increases in reduction potentials can be attributed to subtle differences in the hydrogen‐bonding network in secondary coordination sphere around the T1Cu center.