Abstract

Monoclonal antibody (mAb) MN423 recognizes Alzheimers disease specific conformation of tau protein assembled into paired helical filaments (PHF). Since the three-dimensional structure of PHF is currently unavailable, the structure of MN423 binding site could provide important information about PHF conformation with the consequences for the Alzheimers disease prevention and cure. Fab fragment of MN423 was prepared and purified. We have identified two different conditions for crystallization of the Fab fragment that yielded two crystal forms. They diffracted to 3.0 and 1.6 Å resolution with four and one molecule in the asymmetric unit, respectively. Both crystal forms belonged to the space group P21 with unit cell parameters a = 76.4 Å, b = 138.4 Å, c = 92.4 Å, β = 101.9∞, and a = 71.5 Å, b = 36.8 Å, c = 85.5 Å , β = 113.9∞.

Keywords: Alzheimer's disease, Paired Helical Filaments, Fab fragment, Crystallization, X-ray data