Pteridines
From Biocrawler, the free encyclopedia.
The pteridines are a group of heterocyclic compounds containing a wide variety of substitutions on the basic compound pterin.
Pterin itself is a composed of a pyrazine ring and a pyrimidine ring; the pyrimidine ring has a carbonyl oxygen and an amino group. The biosynthesis of pterins begins with the molecule guanosine triphosphate (GTP); the enzyme which controls the conversion of GTP to pterin, GTP cyclohydrolase, is found in both prokaryotes and eukaryotes.
Pterins were first discovered in the pigments of butterfly wings (hence the origin of their name, from the Greek pteron, wing) and perform many roles in coloration in the biological world. Pterins also function as cofactors in enzymatic catalysis. Folates, “conjugated” pterins which contain para-aminobenzoic acid and glutamates in addition to the pterin ring system, are critical compounds in methyl transfer biochemistry. Tetrahydrobiopterin, the major unconjugated pterin in vertebrates, is involved in the hydroxylation of aromatic compounds and synthesis of nitric oxide. Molybdopterin, which contains pterin, a third heterocyclic ring containing an ether oxygen and two thiol substituents, and molybdenum, is involved in biological hydroxylations, reduction of nitrate, and respiratory oxidation.
