<jats:title>ABSTRACT</jats:title> <jats:p> β-Lactamase inhibitory protein II (BLIP-II) is a potent inhibitor of class A β-lactamases. KPC-2 is a class A β-lactamase that is capable of hydrolyzing carbapenems and has become a widespread source of resistance to these drugs for Gram-negative bacteria. Determination of association and dissociation rate constants for binding between BLIP-II and KPC-2 reveals a very tight interaction with a calculated ( <jats:italic>k</jats:italic> <jats:sub>off</jats:sub> / <jats:italic>k</jats:italic> <jats:sub>on</jats:sub> ) equilibrium dissociation constant of 76 fM (76 × 10 <jats:sup>−15</jats:sup> M).