2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase

In enzymology, a 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase (EC 2.7.6.3) is an enzyme that catalyzes the chemical reaction

ATP + 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine ${\displaystyle \rightleftharpoons }$ AMP + (2-amino-4-hydroxy-7,8-dihydropteridin-6-yl)methyl diphosphate

2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase
2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase monomer, E.Coli
Identifiers
EC no.	2.7.6.3
CAS no.	37278-23-2
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
Search PMC articles PubMed articles NCBI proteins

7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase (HPPK)
7,8-dihydro-6-hydroxymethylpterin-pyrophosphokinase from haemophilus influenzae
Identifiers
Symbol	HPPK
Pfam	PF01288
InterPro	IPR000550
PROSITE	PDOC00631
SCOP2	1hka / SCOPe / SUPFAM
CDD	cd00483
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Thus, the two substrates of this enzyme are ATP and 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine, whereas its two products are AMP and (2-amino-4-hydroxy-7,8-dihydropteridin-6-yl)methyl diphosphate.

This enzyme belongs to the family of transferases, specifically those 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. This enzyme participates in folate biosynthesis.

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.^[1] In the lower eukaryote Pneumocystis carinii, HPPK is the central domain of a multifunctional folate synthesis enzyme (gene fas).^[2]

Structural studies

As of late 2007, 23 structures have been solved for this class of enzymes, with PDB accession codes 1DY3, 1EQ0, 1EQM, 1EX8, 1F9H, 1F9Y, 1G4C, 1HKA, 1HQ2, 1IM6, 1KBR, 1Q0N, 1RAO, 1RB0, 1RTZ, 1RU1, 1RU2, 1TMJ, 1TMM, 2BMB, 2CG8, 2F63, and 2F65.