Aminodeoxychorismate synthase

In enzymology, an aminodeoxychorismate synthase (EC 2.6.1.85) is an enzyme that catalyzes the chemical reaction

chorismate + L-glutamine

⇌

{\displaystyle \rightleftharpoons }

4-amino-4-deoxychorismate + L-glutamate

Thus, the two substrates of this enzyme are chorismate and L-glutamine, whereas its two products are 4-amino-4-deoxychorismate and L-glutamate.

It is part of a pathway for the biosynthesis of para-aminobenzoic acid (PABA); a precursor for the production of folates. Folates are family of cofactors that are essential for living organisms. Folate cofactors are used in several one-carbon transfer reactions required during the synthesis of essential metabolites, including methionine and thymidylate.

Aminodeoxychorismate synthase (PabB), a 51 kDa protein in E. coli, is encoded by the gene pabB. 4-amino-4-deoxychorismate, the product of PabB, can be converted to para-aminobenzoic acid by the enzyme 4-amino-4-deoxychorismate lyase (PabC).

Nonmenclature

This enzyme belongs to the class of transferases. This means that aminodeoxychorismate synthase catalyzes the transfer of one functional group from a molecule to another. Specifically, aminodeoxychorismate synthase is a transaminase that transfers an amino group to a keto acid. The systematic name is Chorismate:L-glutamine aminotransferase. Formerly aminodeoxychorismate synthase was referred to as PABA synthase; however this name is no longer recommended as it is understood that the formation of PABA requires the action of a further enzyme (4-amino-4-deoxychorismate lyase).