RESUMO
Amyloid-ß peptide (1-42) (Aß1-42) is a key player in the development and progression of Alzheimer's disease (AD) and related pathologies, determined by formation of protein aggregates in the central nervous system. Aß1-42 binding to crucial intracellular targets (and their subsequent inactivation) obviously represents one of the earliest events preceding extracellular pathogenic oligomerization/aggregation of Aß1-42. It is reasonable to expect that dissociation of the Aß1-42 complexes with intracellular proteins by means of inhibitors followed by subsequent degradation of Aß1-42 would not only protect critically important proteins but also prevent intracellular accumulation of Aß1-42. The aim of this study was to investigate the effect of the neuroprotector isatin (100 mM) on interaction of known Aß-binding proteins, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and pyruvate kinase, with Aß1-42 and its fragments (Aß1-28, Aß12-28, Aß25-35). Aß1-42 and its fragments (Aß1-28, Aß12-28, Aß25-35) immobilized on the Biacore optical biosensor chip interacted with GAPDH and pyruvate kinase. The lowest and basically equal Kd values were determined for GAPDH and pyruvate kinase complexes with immobilized Aß1-42 and Aß25-35. The presence of 100 mM isatin caused a significant (more than fivefold) increase in the Kd values for GAPDH complexes with all Aß peptides except Aß1-28. In contrast to GAPDH isatin increased dissociation of pyruvate kinase complexes only with Aß1-42 (causing a 30-fold increase in Kd) and to a lesser extent with Aß12-28 and Aß25-35 (a 10-fold increase in Kd). It should be noted that in the presence of isatin the Kd values for GAPDH and pyruvate kinase complexes with all Aß studied were in a narrower concentration range (10-7 M - 10-6 M) than in the absence of this neuroprotector (10-8 M - 10-6 M). Data obtained suggest existence of principal possibility of (pharmacological) protection of crucial intracellular targets against both Aß1-42, and its aggressive truncated peptides (Aß25-35).