Mossbauer properties of the diferric cluster and the differential iron(II)-binding affinity of the iron sites in protein R2 of class Ia Escherichia coli ribonucleotide reductase: a DFT/electrostatics study.

ABSTRACT: The R2 subunit of class-Ia ribonucleotide reductase (RNR) from Escherichia coli (E. coli) contains a diiron active site. Starting from the apo-protein and Fe(II) in solution at low Fe(II)/apoR2 ratios, mononuclear Fe(II) binding is observed indicating possible different Fe(II) binding affinities for the two alternative sites. Further, based on their Mössbauer spectroscopy and two-iron-isotope reaction experiments, Bollinger et al. (J. Am. Chem. Soc., 1997, 119, 5976-5977) proposed that the site Fe1, which bonds to Asp84, should be associated with the higher observed (57)Fe Mössbauer quadrupole splitting (2.41 mm s(-1)) and lower isomer shift (0.45 mm s(-1)) in the Fe(III)Fe(III) state, site Fe2, which is further from Tyr122, should have a greater affinity for Fe(II) binding than site Fe1,

SUBMITTER: Han WG 

PROVIDER: S-EPMC3604995 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature