In enzymology, a pyridoxal kinase (EC 2.7.1.35) is an enzyme that catalyzes the chemical reaction

ATP + pyridoxal ${\displaystyle \rightleftharpoons }$ ADP + pyridoxal 5'-phosphate

Thus, the two substrates of this enzyme are ATP and pyridoxal, whereas its two products are ADP and pyridoxal 5'-phosphate.

This enzyme belongs to the family of transferases, specifically those transferring phosphorus-containing groups (phosphotransferases) with an alcohol group as acceptor. The systematic name of this enzyme class is ATP:pyridoxal 5'-phosphotransferase. Other names in common use include pyridoxal kinase (phosphorylating), pyridoxal 5-phosphate-kinase, pyridoxal phosphokinase, and pyridoxine kinase. This enzyme participates in vitamin B₆ metabolism.

Structural studies

As of late 2007, 15 structures have been solved for this class of enzymes, with PDB accession codes 1LHP, 1LHR, 1RFT, 1RFU, 1RFV, 1TD2, 1VI9, 1YGJ, 1YGK, 1YHJ, 2AJP, 2DDM, 2DDO, 2DDW, and 2F7K.