Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10872430 | FEBS Letters | 2007 | 5 Pages |
Abstract
Ribonucleotide reductase (class I) contains two components: protein R1 binds the substrate, and protein R2 normally has a diferric site and a tyrosyl free radical needed for catalysis. In Chlamydia trachomatis RNR, protein R2 functions without radical. Enzyme activity studies show that in addition to a diiron cluster, a mixed manganese-iron cluster provides the oxidation equivalent needed to initiate catalysis. An EPR signal was observed from an antiferromagnetically coupled high-spin Mn(III)-Fe(III) cluster in a catalytic reaction mixture with added inhibitor hydroxyurea. The manganese-iron cluster in protein R2 confers much higher specific activity than the diiron cluster does to the enzyme.
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Authors
Nina Voevodskaya, Friedhelm Lendzian, Anders Ehrenberg, Astrid Gräslund,