Deuterated Protein Sample Preparation

Two sets of U-¹³C,¹⁵N,²H-CA_CTD-SP1/IP6 samples were prepared, one in Buffer A (20 mM Tris, pD 8.0, 0.5 M NaCl; made from 1 M Tris stock at 99.9% purity in D₂O (Cambridge) and pD adjusted with deuterium chloride (Sigma) prepared in D₂O at 99.9% purity (Cambridge)) and the second in Buffer B (20 mM Tris, pH 8.0, 0.5 M NaCl). The protein samples in Buffer A were prepared by buffer exchange as follows: 0.5 mL protein at 10 mg/mL was diluted into 10 mL with Buffer A then re-concentrated via centrifugation, 4 times. After exchange, the samples were recovered in a final volume 0.5 mL, with concentrations between 9–10 mg/mL.