acetyl-CoA + formate = CoA + pyruvate Activated by pfl-activating enzyme under anaerobic conditions via generation of an organic free radical. Fermentation; pyruvate fermentation; formate from pyruvate: step 1/1. Homodimer. Several mechanisms have been proposed based on complexes formed with substrate analogs. After activation by the glycine radical, the cysteine radical, Cys-414, can abstract hydrogen atoms from the other active site cysteine, Cys-413, and from coenzyme A, and it can also transfer hydrogen atoms to product radicals. The other active site cysteine can attack the central carbonyl of pyruvate and covalently bind the product acetyl group (By similarity). Belongs to the glycyl radical enzyme (GRE) family. PFL subfamily.