Abstract
Cu2+ uptake by A. nidulans wild type was concentration dependent and followed Michaelis-Menten type kinetics with saturating concentration at 25μM. A Lineweaver-Burk plot of the data revealed an apparent Km of 16.6μM and a Vmax value of 2.5nmol mg-1 protein min-1. No characteristic pH profile was evident for Cu2+ uptake in a pH range of 4.0-9.0, although the highest uptake rate was at pH 4.0. Uptake was sensitive to protonophore FCCP, suggesting the involvement of a proton gradient. Uptake was uninhibited in the dark or in the presence of DCCD, indicating that energy generated through ATP hydrolysis may not be directly involved in the uptake process. Genetic control of the transport was suggested on the ground that mutants differed among themselves as well as from the wild type in terms of Km and Vmax values.
