SuiB catalytic mechanism
The catalytic mechanism of SuiB with key radical intermediates detected by EPR.

Trapping a cross-linked lysine–tryptophan radical in the catalytic cycle of the radical SAM enzyme SuiB

Collaborative work between the Britt, Tantillo and Seyedsayamdost (Princeton University) labs uncovers the mechanism for a C–C bond forming streptococcal radical SAM enzyme, SuiB. SuiB is capable of cyclizing a precursor peptide to form a novel natural product called Streptide. The work, recently published in PNAS:, describes a step-by-step mechanism for an unusual radical electrophilic aromatic substitution mechanism through trapping several otherwise fleeting EPR-active intermediates.