Involved in the degradation of isopropylamine, which is a constituent of the herbicides atrazine. Catalyzes the hydrolysis of gamma-glutamyl-L-alaninol (GALO) to L-alaninol and L-glutamate. It can also uses gamma-glutamyl-isopropylamide, gamma-glutamyl-ethylamide, L-glutamine, and gamma-glutamyl-p-nitroanilide. gamma-L-glutamyl-L-alaninol + H2O = L-alaninol + L-glutamate Cells lacking this gene are unable to transform isopropylamine to L-alaninol.