6BQK:
reference: Potent Inhibitors of Hepatitis C Virus NS3 Protease: Employment of a Difluoromethyl Group as a Hydrogen-Bond Donor., Zheng B, D'Andrea SV, Sun LQ, Wang AX, Chen Y, Hrnciar P, Friborg J, Falk P, Hernandez D, Yu F, Sheaffer AK, Knipe JO, Mosure K, Rajamani R, Good AC, Kish K, Tredup J, Klei HE, Paruchuri M, Ng A, Gao Q, Rampulla RA, Mathur A, Meanwell NA, McPhee F, Scola PM, ACS Med Chem Lett. 2018 Jan 19;9(2):143-148. doi: 10.1021/acsmedchemlett.7b00503., eCollection 2018 Feb 8. PMID: 29456803

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