2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase () is an enzyme that catalyzes the chemical reaction
The enzyme characterised from Escherichia coli converts 6-hydroxymethyl-7,8-dihydropterin to 2-amino-4-hydroxy-6-pyrophosphoryl-methylpteridine by transferring a pyrophosphate group from the cofactor, adenosine triphosphate (ATP), which is converted to adenosine monophosphate (AMP).
This enzyme catalyses the first step in a three-step pathway leading to 7,8 dihydrofolate. Bacterial HPPK (gene folK or sulD) is a protein of 160 to 270 amino acids. In the lower eukaryote Pneumocystis carinii, HPPK is the central domain of a multifunctional folate synthesis enzyme (gene fas).
Nomenclature The enzyme is a transferases, specifically one transferring two phosphorus-containing groups (diphosphotransferases). The systematic name of this enzyme class is ATP:2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine 6'-diphosphotransferase. Other names in common use include 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine pyrophosphokinase, H2-pteridine-CH2OH pyrophosphokinase, 7,8-dihydroxymethylpterin-pyrophosphokinase, HPPK, 7,8-dihydro-6-hydroxymethylpterin pyrophosphokinase, and hydroxymethyldihydropteridine pyrophosphokinase.
Structural studies As of late 2007, 23 structures have been solved for this class of enzymes, with Protein Data Bank accession codes , , , , , , , , , , , , , , , , , , , , , , and .
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