B. Delgadocoello et J. Masoliva, LEAD AFFECTS THE FORMATION OF THE PHOSPHORYLATED INTERMEDIATE ON THE (CA2-ATPASE FROM HUMAN ERYTHROCYTES(,MG2+)), Medical science research, 24(3), 1996, pp. 159-161
The effect of lead on the (Ca2+,Mg2+)-ATPase (EC 3.6.1.38) of erythroc
yte membranes is investigated. The presence of lead in the reaction mi
xture, depending on the temperature of incubation, causes an important
decrease in ATPase activity. The presence of calmodulin also modulate
s this effect. The results suggest that calmodulin accelerates the dep
hosphorylation of the phosphorylated intermediates and that lead imped
es their formation. Together, the two effects, on the one hand lead pr
eventing the formation of the intermediates, and on the other calmodul
in allowing the rapid hydrolysis of the intermediates, would explain e
mploying rapid kinetics, the almost instantaneous deactivation of the
enzyme.