In
enzymology
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
, a GTP cyclohydrolase II () is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
that
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
the
chemical reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
:GTP + 3 H
2O
formate + 2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine + diphosphate
Thus, the two
substrates of this enzyme are
GTP and
H2O, whereas its 3
products are
formate
Formate (IUPAC name: methanoate) is the conjugate base of formic acid. Formate is an anion () or its derivatives such as ester of formic acid. The salts and esters are generally colorless.Werner Reutemann and Heinz Kieczka "Formic Acid" in ''Ull ...
,
2,5-diamino-6-hydroxy-4-(5-phosphoribosylamino)pyrimidine, and
diphosphate.
This enzyme belongs to the family of
hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amidines. The
systematic name of this enzyme class is GTP 7,8-8,9-dihydrolase (diphosphate-forming). Other names in common use include guanosine triphosphate cyclohydrolase II, and GTP-8-formylhydrolase. This enzyme participates in
riboflavin metabolism
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in e ...
.
Structural studies
As of late 2007, two
structures have been solved for this class of enzymes, with
PDB accession codes and .
References
*
EC 3.5.4
Enzymes of known structure
{{3.5-enzyme-stub