Reaction catalyzed by diphthine synthase (2.1.1.98)

3		+			=	3		+		diphthine-[translation elongation factor 2]
	3 S-adenosyl-L-methionine	+		2-[(3S)-3-carboxy-3-aminopropyl]-L-histidine-[translation elongation factor 2]	=		3 S-adenosyl-L-homocysteine	+		diphthine-[translation elongation factor 2]