2.4.1.202	Cu2+	5 mM, 3% remaining activity	
2.4.1.202	EDTA	16% decrease of activity	
2.4.1.202	Fe2+	5 mM, 5% remaining activity	
2.4.1.202	N-ethylmaleimide	at 1 mM, 96% decrease of activity, after addition of dithioerythritol, full activity