1CK3:
reference: X-ray structure of the Asn276Asp variant of the Escherichia coli TEM-1 beta-lactamase: direct observation of electrostatic modulation in resistance to inactivation by clavulanic acid., Swaren P, Golemi D, Cabantous S, Bulychev A, Maveyraud L, Mobashery S, Samama JP, Biochemistry 1999 Jul 27;38(30):9570-6. PMID: 10423234

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