Reaction catalyzed by 1-aminocyclopropane-1-carboxylate deaminase (3.5.99.7), threonine ammonia-lyase (4.3.1.19), cystathionine gamma-lyase (4.4.1.1), homocysteine desulfhydrase (4.4.1.2)

		=
	2-aminobut-2-enoate	=		2-iminobutanoate