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

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

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.