(b).

	Residual activity (%)
	Free enzyme	Entrapped enzyme	Cross-linked
Metal ions (5 mM)
NaCl	124.9 ± 5.66	73.6 ± 2.92	74.2 ± 3.21
KCl	166.6 ± 6.84	92.1 ± 4.25	96.9 ± 4.47
MgCl2	93.8 ± 3.62	57.5 ± 2.43	63.5 ± 3.02
CaCl2	84.6 ± 2.68	87.6 ± 3.73	80.6 ± 3.45
CoCl2	33.4 ± 1.32	41.1 ± 1.64	38.0 ± 1.12
HgCl2	9.8 ± 1.02	37.04 ± 2.46	39.9 ± 1.82
CdCl2	15.9 ± 1.68	36.8 ± 2.37	35.9 ± 2.54
NiCl2	59.9 ± 5.23	47.4 ± 4.02	49.8 ± 4.17
Lead acetate	35.2 ± 2.63	73.2 ± 3.61	78.9 ± 4.23
Chemicals (1 mM)
PMSF∗	97.3 ± 5.62	104.9 ± 6.10	127.3 ± 6.55
PHMB#	4.7 ± 0.58	34.7 ± 2.81	47.6 ± 3.19
DTNB†	5.0 ± 0.95	29.4 ± 1.66	53.2 ± 2.58
EDTA‡	90.8 ± 6.24	82.71 ± 5.77	84.5 ± 5.29

^∗PMSF: phenylmethanesulfonyl fluoride.

^#PHMB: para-hydroxymercurybenzoate.

^†DTNB: 5,5′-dithiobis-(2-nitrobenzoic acid).

^‡EDTA: ethylenediaminetetraacetic acid.