NMR spectroscopy of purified MAβ:ZAβ3 complex. (A) 15N HSQC NMR spectrum of the 15N-labeled MAβ(1–40):ZAβ3 complex. The complex was obtained from coexpression and purified by IMAC (elution of the intact complex with 150 mM imidazole) and SEC. (B)-(D) Comparison of the glycine region (B; boxed area in panel A) with corresponding regions of 15N HSQC spectra of Aβ(1–40):ZAβ3 samples in which either ZAβ3 (C) or Aβ(1–40) (D) are 15N-labeled. Sequential assignments of glycine resonances for the two ZAβ3 subunits and bound Aβ(1–40) are given in panels C and D, respectively. The occurrence of resonances at identical chemical shifts in complexes of ZAβ3 with recombinant MAβ(1–40) and native Aβ(1–40) peptides indicates that the structures of the two complexes are the same. NMR was measured at 25°C at 800 MHz (A, B and D) or 900 MHz (C) on samples containing 160 μM (A, B), 450 μM (C) or 400 μM (D) complex in 20 mM potassium (A, B) or sodium (C, D) phosphate, with 0.1% azide and 10% D2O at pH 7.2.
Macao et al. BMC Biotechnology 2008 8:82 doi:10.1186/1472-6750-8-82