4I6O:
reference: Efficient chemical synthesis of human complement protein C3a., Ghassemian A, Wang CI, Yau MK, Reid RC, Lewis RJ, Fairlie DP, Alewood PF, Durek T, Chem Commun (Camb). 2013 Feb 21;49(23):2356-8. doi: 10.1039/c3cc40537k. PMID: 23407800

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