A new fluorescence at 333 nm formed when the solution of human neuronal tau
protein was incubated at 37 degrees C. The maximum excitation was at 230 a
nd 280 nm respectively with the quantum yield of about 0.02. It took about
30 h for the complete formation of the new fluorescence and the light scatt
ering increased with the formation procedure. It suggests that the fluoresc
ence resulted from the aggregation of tau molecules in solution.