2XSK:
reference: Extending the usability of the phasing power of diselenide bonds: SeCys SAD phasing of CsgC using a non-auxotrophic strain., Salgado PS, Taylor JD, Cota E, Matthews SJ, Acta Crystallogr D Biol Crystallogr. 2011 Jan;67(Pt 1):8-13. Epub 2010 Dec, 16. PMID: 21206057

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