Forms part of the defence mechanism against insects and microbial pathogens in the grass family, Gramineae, where it catalyses one of the steps in the formation of the cyclic hydroxamic acids 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA) and 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) [1]. This enzyme resembles the ¦Á-subunit of EC?4.2.1.20, tryptophan synthase [3] but, unlike tryptophan synthase, its activity is independent of the ¦Â-subunit and free indole is released [2].
