Microcalorimetric study of Tetrahymena growth affected by copperII complexes

By means of microcalorimetry, the effect of four copper(II) complexes on Tetrahymena growth was investigated. The extent and duration of the inhibitory effect on the metabolism, judged by the rate constant, k, and the half inhibition concentration, IC(50), varied with the different complexes. The results showed that the half inhibition concentrations IC(50) of CuCl(2), (C(9)H(6)NO)(2)Cu and [Cu(phen)(2)]Cl(2)[Symbol: see text]6H(2)O were 9.9 x 10(-4), 2.0 x 10(-4), and 2.6 x 10(-4) mol/L, respectively. The sequence of antibiotic activity of these three complexes was: (C(9)H(6)NO)(2)Cu > [Cu(phen)(2)]Cl(2)[Symbol: see text]6H(2)O > CuCl(2). The growth rate constants of [Cu(phen)(3)]Cl(2)[Symbol: see text]6H(2)O did not change obviously with the increase of concentrations, but [Cu(phen)(3)]Cl(2)[Symbol: see text]6H(2)O also can prolong the time of Tetrahymena growth.