1.5.3.20	CuSO4	2 mM, 53% residual activity	
1.5.3.20	iodoacetic acid	2 mM, 28% residual activity	
1.5.3.20	p-chloromercuribenzoic acid	0.2 mM, 38% residual activity	
1.5.3.20	sodium dodecylsulfate	2 mM, 34% residual activity	
1.5.3.20	ZnSO4	2 mM, 30% residual activity