4IUZ:
reference: Fully Convergent Chemical Synthesis of Ester Insulin: Determination of the High Resolution X-ray Structure by Racemic Protein Crystallography., Avital-Shmilovici M, Mandal K, Gates ZP, Phillips NB, Weiss MA, Kent SB, J Am Chem Soc. 2013 Feb 8. PMID: 23343390

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