Fold: PFL-like glycyl radical enzymes

contains: barrel, closed; n=10, S=10; accommodates a hairpin loop inside the barrel

Lineage:

1. Root: scop
2. Class: Alpha and beta proteins (a/b)
   Mainly parallel beta sheets (beta-alpha-beta units)
3. Fold: PFL-like glycyl radical enzymes
   contains: barrel, closed; n=10, S=10; accommodates a hairpin loop inside the barrel

Superfamilies:

1. PFL-like glycyl radical enzymes (3)
   duplication: the N- and C-terminal halves have similar topologies
   1. Pyruvate formate-lyase, PFL (1)
   2. R1 subunit of ribonucleotide reductase, C-terminal domain (1)
   3. Class III anaerobic ribonucleotide triphosphate reductase NRDD subunit (1)