An enzyme that catalyzes the first step in the biosynthetic pathway to LEUCINE, forming isopropyl malate from acetyl-CoA and alpha-ketoisovaleric acid. This enzyme was formerly listed as EC 4.1.3.12.

Synonyms: alpha-Isopropylmalate Synthase, 2-Isopropylmalate Synthase, 2 Isopropylmalate Synthase, alpha Isopropylmalate Synthase, EC 2.3.3.13, Synthase, 2-Isopropylmalate, 3-Carboxy-3-hydroxy-4-methylpentanoate 3-methyl-2-oxobutanoate-lyase (CoA-acetylating), Synthase, alpha-Isopropylmalate