Amyloid fibril preparation
Recombinant wild-type β2m was expressed in Escherichia coli and purified to homogeneity.26 The recombinant wild-type protein contained all 99 residues plus the N-terminal methionine, and the single disulfide bond was oxidised. Fibrils were formed by incubation of the protein (0.3–0.5 mg/ml) for 2–8 weeks at pH 2.5 in 25 mM sodium phosphate and 25 mM sodium acetate buffer containing 0.03% (wt/vol) sodium azide at 37 °C. At pH 7.0, fibrils were grown by elongation of heparin-stabilised seeds from fibrils formed at pH 2.5.24