Binding of allosteric effectors to ribonucleotide reductase protein R1: reduction of active-site cysteines promotes substrate binding.
Eriksson, M., Uhlin, U., Ramaswamy, S., Ekberg, M., Regnstrom, K., Sjoberg, B.M., Eklund, H.(1997) Structure 5: 1077-1092
- PubMed: 9309223 
- DOI: https://doi.org/10.1016/s0969-2126(97)00259-1
- Primary Citation of Related Structures:  
1R1R, 2R1R, 3R1R, 4R1R - PubMed Abstract: 
Ribonucleotide reductase (RNR) is an essential enzyme in DNA synthesis, catalyzing all de novo synthesis of deoxyribonucleotides. The enzyme comprises two dimers, termed R1 and R2, and contains the redox active cysteine residues, Cys462 and Cys225. The reduction of ribonucleotides to deoxyribonucleotides involves the transfer of free radicals. The pathway for the radical has previously been suggested from crystallographic results, and is supported by site-directed mutagenesis studies. Most RNRs are allosterically regulated through two different nucleotide-binding sites: one site controls general activity and the other controls substrate specificity. Our aim has been to crystallographically demonstrate substrate binding and to locate the two effector-binding sites.
Organizational Affiliation: 
Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala Biomedical Center, Sweden.