Toxic binding of cupric ion by marine phytoplankton

Abstract

The data presented by Gavis et al. (1981) for the specific growth rate of phytoplankton in nutrient replete medium as a function of cupric ion activity can be described quantitatively by equations that relate the equilibrium binding of cupric ions to a cell receptor site. Statistically significant conditional binding constants could be estimated from the data for at least 8 clones among 3 spp. One clone could bind only 1 cupric ion/site. The others could bind a maximum of 2 cupric ions/site. For one of these clones K1 [equilibrium binding constant] > K2. For the remaining 6 K2 > K1. For 3 clones K2 was so much larger than K1 that only their product, .beta.2, could be determined. Values of K1 ranged between 8.6 .times. 108 and 5.7 .times. 1010, values of K2 ranged between 3.1 .times. 108 and 1.9 .times. 1010, while those of .beta.2 ranged between 3.5 .times. 1019 and 3.8 .times. 1020.