The

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

imidazoleglycerol-phosphate dehydratase ()

catalyzes Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

the

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

:D-erythro-1-(imidazol-4-yl)glycerol 3-phosphate

\rightleftharpoons

3-(imidazol-4-yl)-2-oxopropyl phosphate + H₂O This enzyme belongs to the family of

lyase In biochemistry, a lyase is an enzyme that catalyzes the breaking (an elimination reaction) of various chemical bonds by means other than hydrolysis (a substitution reaction) and oxidation Redox ( , , reduction–oxidation or oxidatio ...

s, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

of this enzyme class is D-''erythro''-1-(imidazol-4-yl)glycerol-3-phosphate hydro-lyase -(imidazol-4-yl)-2-oxopropyl-phosphate-forming''. Other names in common use include IGP dehydratase, and D-''erythro''-1-(imidazol-4-yl)glycerol 3-phosphate hydro-lyase. This enzyme participates in

histidine metabolism Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the d ...

as it is involved in the 6th step of histidine biosynthesis as part of a nine step cyclical pathway. There are two isoforms of IGPD; IGPD1 and IGPD2. The different isoforms are highly conserved with only 8 amino acids differing between them. These subtle differences however affect their activity but as yet it is unknown how. In most

organism An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...

s IGPD is a monofunctional

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

of about 22 to 29 kD. In some bacteria such as ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

'', it is the

C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, carboxy tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When t ...

domain A domain is a geographic area controlled by a single person or organization. Domain may also refer to: Law and human geography * Demesne, in English common law and other Medieval European contexts, lands directly managed by their holder rather ...

of a bifunctional protein that include a histidinol-phosphatase domain. In ''E. coli'', this is the protein encoded by the '' hisB'' gene.

Inhibition

Certain compounds that inhibit IGPD have been used as

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

s as animals do not have this protein. One of these inhibitors is

3-Amino-1,2,4-triazole 3-Amino-1,2,4-triazole (3-AT) is a heterocyclic organic compound that consists of 1,2,4-triazole with an amino group as a substituent. 3-AT is a competitive inhibitor of the product of the HIS3 gene, imidazoleglycerol-phosphate dehydratase. Im ...

(3-AT), which has also been used as a competitive inhibitor of the product of the

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...

HIS3 The HIS3 gene, found in the ''Saccharomyces cerevisiae'' yeast, encodes a protein called Imidazoleglycerol-phosphate dehydratase which catalyses the sixth step in histidine biosynthesis. It is analogous to hisB in ''Escherichia coli''. Exploits ...

gene (another IGPD), e.g. in the

yeast two-hybrid system Two-hybrid screening (originally known as yeast two-hybrid system or Y2H) is a molecular biology technique used to discover protein–protein interactions (PPIs) and protein–DNA interactions by testing for physical interactions (such as bindi ...

Structural studies

As of late 2007, 3

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

have been solved for this class of enzymes, with PDB accession codes , , and .

Inhibition

Structural studies

References

Further reading