Protein minimization by random fragmentation and selection.

Protein-protein interactions are involved in most biological processes and are important targets for drug design. Over the past decade, there has been increased interest in the design of small molecules that mimic functional epitopes of protein inhibitors. BLIP is a 165 amino acid protein that is a potent inhibitor of TEM-1 beta-lactamase (K(i) = 0.1 nM). To aid in the development of new inhibitors of beta-lactamase, the gene encoding BLIP was randomly fragmented and DNA segments encoding peptides that retain the ability to bind TEM-1 beta-lactamase were isolated using phage display. The selected peptides revealed a common, overlapping region that includes BLIP residues C30-D49. Synthesis and binding analysis of the C30-D49 peptide indicate that this peptide inhibits TEM-1 beta-lactamase. Therefore, a peptide derivative of BLIP that has been reduced in size by 88% compared with wild-type BLIP retains the ability to bind and inhibit beta-lactamase.