<p>In <taxon tax_id="562">Escherichia coli</taxon> and related bacteria, the pflA protein (or act) [<cite idref="PUB00001367"/>] is involved (<db_xref db="EC" dbkey="1.97.1.4"/>) in the activation of pyruvate formate-lyase (gene pflB) under anaerobic conditions by generation of an organic free radical, using S-adenosylmethionine and reduced flavodoxin as cosubstrates to produce 5'-deoxy-adenosine. The activity of pflA is iron-dependent. A protein highly similar to pflA and termed pflC [<cite idref="PUB00003594"/>] is probably involved in the activation of a second pyruvate format lyase (gene pflD). The pflA/pflC proteins belong to a family that also includes <taxon tax_id="10665">Bacteriophage T4</taxon> and E. coli nrdG which are involved [<cite idref="PUB00002923"/>] in the generation of the free radical for the anaerobic ribonucleoside-triphosphate reductase (gene nrdD or sunY). It also includes E. coli hypothetical protein yjjW, <taxon tax_id="727">Haemophilus influenzae</taxon> hypothetical protein HI0520 and <taxon tax_id="2190">Methanocaldococcus jannaschii</taxon> (Methanococcus jannaschii) hypothetical protein MJ0021. All these proteins possess, in their N-terminal section, a highly conserved region which contains three clustered cysteines which could be involved in iron-binding.</p> Radical-activating enzyme, conserved site