Investigating the intermediates in the reaction of ribonucleoside triphosphate reductase from Lactobacillus leichmannii: An application of HF EPR-RFQ technology

► We study the exchange-coupled thiyl radical-cob(II)alamin system. ► We refine the size of the exchange coupling of the thiyl radical g tensor. ► The distance between the paramagnets is consistent with previous work. ► We developed and used a unique rapid-freeze quench apparatus for preparation of samples for use with high-field EPR.