Heavy metal ion inhibition studies of human, sheep and fish α-carbonic anhydrases

Figures & data

Table 1.  K_i values for the inhibition of hCA I, hCA II, dCA and sCA IV with metal ions by an esterase method with 4-NPA as substrate²⁷.

Inhibitor	Ki hCA I (mM)	Ki hCA II (mM)	Ki dCA (mM)	Ki sCA IV (mM)
Pb^2+	0.99^a	0.056^a	0.24^b	1.13
Co^2+	3.91^a	1.70^a	0.53^b	NI
Hg^2+	1.42^a	0.31^a	0.77^b	NI
Cd^2+	2.18	0.24	0.21	1.04
Zn^2+	4.41	2.78	0.72^b	0.96
Se^2+	2.34	1.97	0.98	NT
Cu^2+	0.98	0.16	0.17^b	4.70
Al^3+	1.47	0.58	0.15^b	3.45
Mn^3+	10.78	8.17	3.46	NI

Mean from at least three determinations. Errors in the range of 1–3% of the reported value (data not shown).

NI, no inhibition, less than 30% inhibition at the concentration of 100 mM; NT, no tested.

^aEkinci et al. (2007)²⁵.

^bCeyhun et al. (2011)²².

Figure 1.  SDS-PAGE photograph. Lane 1: Sheep liver CA IV. Lane 2: Standard proteins: rabbit phosphorylase B (97.4 kDa), truncated β-galactosidase (83 kDa), bovine albumin (66 kDa), chicken ovalbumin (45 kDa) and bovine carbonic anhydrase (29 kDa).

Figure 2.  Lineweaver–Burk curves for 4-NPA hydrolysis catalyzed by sheep CA IV enzyme, at five different concentrations of substrate.

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