This document presents on cobalt ribonucleotide reductase, which reduces ribonucleotides to deoxyribonucleotides. It discusses the three classes of ribonucleotide reductase and their structures. It also covers the reaction mechanism, showing the electronic states of cobalt as it transitions between cobalt(II), cobalt(I), and cobalt(III) states in the reaction, with cobalt(I) forming a radical intermediate. Key cobalt-containing cofactors in the reaction are also defined.

1. Cobalt ribonucleotide reductase
CH-594)
Presented by
Sandeep Kumar Yadav
(15I030004)
Department of Chemistry
Indian Institute of Technology
Bombay
March 2017
1

2. Cobalt ribonucleotide reductase
• Introduction
• Class I , II and III RNR
• Structures
• Reaction
• Mechanism

3. Cobalt ribonucleotide reductase
B12 cobalamine
B12r Co(II) reduced
B12s Co(I) super-reduced
B12a aquacobalamine
B12b Hydroxycobalamine

4. Reaction and mechanism

6. d (electrophile)
+ve dx
2 2
-y
dz
2
O
dxy
dxz
dyz
-ve Co(II) Co(I)Co(III)
d7 d8(radical) (nucleophile)d6 (electrophile)
B12r B12sB12
Electronic states of Co(I/II/III)