Reaction catalyzed by acyl-CoA dehydrogenase (NADP+) (1.3.1.8), short-chain acyl-CoA dehydrogenase (1.3.8.1)

		+		reduced acceptor	=			+		oxidized acceptor
	crotonyl-CoA	+		reduced acceptor	=		butyryl-CoA	+		oxidized acceptor