Figure 2

Reaction of formaldehyde with amino groups of neuronal tau. (A) Neuronal tau (final concentration 0.1 μM) was resuspended in phosphate buffer containing OPT (20 times molar excess compared to protein) in the presence of formaldehyde at different concentrations at 37°C for 120 min. The fluorescence (Ex340 nm/Em455 nm) was then measured. (B) Under the same conditions, tau was incubated with (curve 1) or without (curve 2) 0.005% formaldehyde and 2 μM OPT. Aliquots were then taken to measure the fluorescence at different time intervals. The data were plotted on a semilogarithmic scale as described by Tsou et al. [59].