Fig. 3.

(Upper panel) Heavy metals-mediated inhibition of human sperm creatine kinase in a vary concentrations of substrate (0-10 mM). Concentrations of 0.3 mM of bismuth (Bi⁺³), 0.3 mM of lead (Pb⁺²), 0.3 mM of mercury (Hg⁺²), 0.5 mM of indium (In⁺³), 0.5 mM of tin (Sn⁺²) and 0.6 mM of silver (Ag⁺²) were used. Results are expressed as mean ± S.D. of triplicate determination. (Lower panel) Lineweaver-Burk plots reflect a probable competitive type inhibition of human sperm creatine kinase activity by heavy metals.