Effect of the β-amyloid peptide Aβ25-35 and fullerene C60 on the activity of enzymes in erythrocytes

The effect of the beta-amyloid peptide A beta(25-35) and fullerene C-60 on the activity of the cytoplasmic enzymes lactate dehydrogenase (LDH) and glutathione peroxidase (GLP), and membrane-bound phosphofructokinase (PFK) and Na+,K+-ATPase in human erythrocytes has been studied. When used in combination, the cytotoxins decrease the activity of LDH and PFK in a nonadditive manner; in this case, A beta(25-35) protects PFK against the inhibitory effect of C-60. The activity of LDH, GLP, and PFK decreases within the first 2-20 min of incubation of erythrocytes with A beta(25-35) in the absence of glucose. The addition of glucose sharply decreases the inhibitory action of A beta(25-35) on LDH and GLP but does not affect the fourfold decrease in activity of PFK; the activity of membrane-bound Na+,K+-ATPase does not depend on the presence of glucose. Possible mechanisms of interaction of A beta(25-35) and fullerene C-60 with the erythrocyte membrane and enzymes are discussed.