In vitro inhibitory effects of some heavy metals on human erythrocyte carbonic anhydrases

Figures & data

Figure 1 SDS-PAGE analysis of purified HCA-I and HCA-II. Lane (1) standard proteins (E.Coli β-galactosidase (116 kDa), rabbit phosphorylase B (97.4 kDa), bovine serum albumin (66 kDa), chicken ovalbumin (45 kDa) and bovine carbonic anhydrase (29 kDa)). Lane (2) HCA-I. Lane (3) HCA-II.

Table I.  Summary of purification procedure for HCA-I and HCA-II.

Purification step	Activity (EU/mL)	Total volume (mL)	Protein (mg/mL)	Total protein (mg)	Total activity (EU)	Specific activity (EU/mg)	Yield (%)	Purification factor
Haemolysate	135	90	15.7	1368	12150	8.88	100	1
HCA-I	368	10	0.4	4	3680	920	30	104
HCA-II	800	6	0.1	0.6	4800	8000	40	900

Table II.  K_i values and inhibition types for 3 inhibitors of HCA-I and HCA-II.

	Ki		Average values of Ki (mM)		Type of inhibition
Inhibitors	HCA-I	HCA-II	HCA-I	HCA-II	HCA-I	HCA-II
Pb(NO3)2	1.33	0.0543	0.99	0.056	Noncompetitive	Uncompetitive
	0.64	0.0553
	1.00	0.0590
CoCl2·6H2O	3.17	1.10	3.91	1.70	Competitive	Noncompetitive
	4.15	1.30
	4.41	2.70
HgCl2	2.12	0.404	1.42	0.312	Uncompetitive	Uncompetitive
	1.35	0.274
	0.81	0.259

Figure 2 Lineweaver-Burk graph using 5 different substrate (4-nitrophenylacetate) concentrations and 3 different Pb⁺² concentrations for determination of K_i for HCA-I.

Figure 3 Lineweaver-Burk graph using 5 different substrate (4-nitrophenylacetate) concentrations and 3 different Pb⁺² concentrations for determination of K_i for HCA-II.