Crystals of Cry11Aa were centrifuged for 5 min at 5000 × g during the buffer wash and washed twice with ammonium acetate buffer (pH adjusted to 6.4 with acetic acid). Pelleted crystals were then dissolved in ammonium acetate buffer (pH adjusted to 11.5 using ammonium hydroxide). Gold-coated capillary emitters were prepared as previously described and used to load the protein sample105 (link). The sample was analyzed on a Synapt G1 mass spectrometer (Waters Corporation). The instrument was tuned to preserve non-covalent interactions. Briefly, the capillary voltage was set to 1.60 kV, the sampling cone voltage was 20 V, the extraction cone voltage was 5 V, the source temperature was 80 °C, the trap transfer collision energy was 10 V, and the trap collision energy (CE) was set at 30 V. For MS/MS characterization, a particular charge state was isolated in the quadrupole and the complex was dissociated by application of 200 V of CE. The data collected were deconvoluted and analyzed using UniDec106 (link).
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