Protein radicals are components of several biologically important reactions.
Glycyl radical enzymes are involved in a great variety of functions, for
example, nucleotide, pyruvate and toluene metabolism . These enzymes are
posttranslationally interconverted, under anaerobic conditions, from an
inactive to an active form that carries a stable radical localized to a
specific glycine at the C-terminal region of the polypeptidic chain. Extreme
sensitivity towards destruction by oxygen, leading to polypeptide cleavage
between the N-Cα bond of the Gly residue, is a conspicuous property of all
protein-based glycyl radicals, thus confining their existence to strictly
Some proteins known to contain a glycyl radical are listed below:
Escherichia coli pyruvate formate-lyase (EC 18.104.22.168) (genes pflB, pflD
and pflF), a key enzyme of anaerobic glucose metabolism, it converts
pyruvate and CoA into acetyl-CoA and pyruvate .
Escherichia coli (gene nrdD) and bacteriophage T4 (gene nrdD or sunY)
anaerobic ribonucleoside-triphosphate reductase (EC 22.214.171.124) [3,4].
These proteins share a conserved region centered around the glycine which, in
pfl, is known to bear the free radical. We use this region has a signature
pattern. We also developed a profile which covers the entire glycine radical
April 2006 / Pattern revised.
PROSITE methods (with tools and information) covered by this documentation:
Eklund H., Fontecave M.
Glycyl radical enzymes: a conservative structural basis for radicals.
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to
or see: prosite_license.html.