b-Lactams have historically been viewed as a class of antimicrobials. However, this paradigm is shifting towards a focus

on their ability to function as inhibitors of bacterial enzymes, particularly those involved in broad-spectrum b-lactam

resistance, i.e., extended spectrum b-lactamases (ESBL). This shift in focus is the result of the recognition of the b-lactam’s

ability to acylate enzymes, the majority of which have serine as the nucleophile in the active site. In addition to being inhibitors

of bacterial enzymes, b-lactams also inhibit viral and mammalian serine enzymes demonstrating inter-kingdom activity. The

focus of this presentation is on the evaluation of the potential of b-lactam antibiotics as inhibitors of the serine enzymes of both

prokaryotic and eukaryotic origin, with the specific focus on the structure-function relationship of b-lactams as antimicrobial and

antineoplastic agents.