In enzymology, a protein-histidine pros-kinase (EC 18.104.22.168) is an enzyme that catalyzes the chemical reaction
- ATP + protein L-histidine ADP + protein Nπ-phospho-L-histidine
Thus, the two substrates of this enzyme are ATP and protein L-histidine, whereas its two products are ADP and protein Npi-phospho-L-histidine.
This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain of histidine residues in proteins (protein-histidine kinases). The systematic name of this enzyme class is ATP:protein-L-histidine Npi-phosphotransferase. Other names in common use include ATP:protein-L-histidine N-pros-phosphotransferase, histidine kinase, histidine protein kinase, protein histidine kinase, protein kinase (histidine), and HK2.