Source and purification of EH7

The vector pBXCH and the host Escherichia coli MC1061 were the sources of His6‐tagged EH₇ (GenBank acc. nr. {"type":"entrez-nucleotide","attrs":{"text":"KY483644","term_id":"1278382519","term_text":"KY483644"}}KY483644) [4], which was produced and purified at 4 °C after binding to a Ni‐NTA His‐Bind resin (from Merck Life Science S.L.U., Madrid, Spain) as described previously [33]. After the Ni‐NTA column, the protein was further purified by size‐exclusion chromatography using a HiLoad 16/60 Superdex 200 column equilibrated in buffer: 40 mm N‐(2‐hydroxyethyl)piperazine‐N′‐(2‐ethanesulfonic acid) (HEPES) pH 7, 50 mm NaCl, 1 mm dithiothreitol (DTT). Two peaks were obtained after purification and concentrated independently: the first peak from 53.5 to 57.5 mL (concentrated at 44 mg·mL⁻¹) and the second peak from 64.5 to 66.5 mL (concentrated at 28 mg·L⁻¹) were stored at 193 K. The purity of all the samples was confirmed by SDS/PAGE.