Selenide, water dikinase

In enzymology, a selenide, water dikinase (EC 2.7.9.3) is an enzyme that catalyzes the chemical reaction

ATP + selenide + H₂O ${\displaystyle \rightleftharpoons }$ AMP + selenophosphate + phosphate

selenide, water dikinase
Identifiers
EC no.	2.7.9.3
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

The 3 substrates of this enzyme are ATP, selenide, and H₂O, whereas its 3 products are AMP, selenophosphate, and phosphate.

This enzyme belongs to the family of transferases, to be specific, those transferring phosphorus-containing groups (phosphotransferases) with paired acceptors (dikinases). The systematic name of this enzyme class is ATP:selenide, water phosphotransferase. This enzyme is also called selenophosphate synthetase. This enzyme participates in selenoamino acid metabolism.

Evolution

Vertebrates including humans carry two versions of this enzyme, with one (SEPHS2) being a selenoprotein and the other (SEPHS1) replacing it with a threonine, though still with a vestigial SECIS element. Analysis of animal versions of this enzyme show that the original animal version is a selenoprotein, with SEPHS1 arising later through gene duplication.^[1]

Among prokaryotes, most bacteria have a version with cystine instad of selenocystine, suggesting that this may be the ancestral state (which would avoid the chicken-and-egg problem). Some have two versions, one with Sec and the other with Cys. Archaea mostly have the Sec version.^[1]