Several different BMC loci have been identified that contain glycyl radical enzymes, which obtain the catalytic radical from the cleavage of s-adenosylcobalamin.

The glycyl radical enzyme is proposed to dehydrate propanediol to propionaldehyde, which is then processed in a manner identical to the canonical PDU BMC.

In addition, the Anaerobic Enzymology Pilot Project was added in 2014 to explore the Radical SAM superfamily and Glycyl Radical Enzyme superfamily.