Studies in Active Site Mutant Enzymes

As expected, mutations at Cys439 (C439A, C439S) are catalytically inert (Mao et al., 1992b berg et al., 1989). Similar results were obtained 

FIGURE 3. Consecutive radical intermediates observed in the suicidal reaction between E. coli E441Q, wild type R2 and substrate (A), including EPR spectra for the transient tyrosyl radical in R2 presumably at Tyr356 (B), the disulphide anion radical at Cys225nCys462 in R1 (C), and the nucleotide-derived radical (D). The arrows in B-D indicate g = 2.005. 

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