FIG. 4.

Evaluation of mercury binding by JM109 cells harboring pUNIM. (A) Effect of sodium ion on mercury binding. Resting cells (0.265 mg [dry weight]) were resuspended in Tris buffer (pH 7.4) containing 5 μM Hg²⁺, and the indicated concentrations of NaCl were added. Hg²⁺ binding was determined after 1 h of incubation. (B) pH profile of mercury binding. Resting cells (0.265 mg [dry weight]) were resuspended in citric-phosphate-borate buffer containing 5 μM Hg²⁺ with pHs ranging from 3 to 11. Hg²⁺ binding was determined after 1 h of incubation. The data shown are the mean values (± standard deviation) obtained from three independent experiments.