Identification of a novel calpain inhibitor using phage display

• Published in: Biochemical and biophysical research communications Vol. 333; no. 4; pp. 1087 - 1092
• Main Authors: Guttmann, Rodney P., Day, George A., Wang, Xiaohong, Bottiggi, Kara A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 12.08.2005
• Subjects: Amino Acid Sequence; Binding Sites; Calcium; Calpain; Calpain - analysis; Calpain - antagonists & inhibitors; Calpain - metabolism; Molecular Sequence Data; Oligopeptides - analysis; Oligopeptides - chemistry; Oligopeptides - metabolism; Peptide; Peptide Library; Peptides - analysis; Peptides - chemistry; Peptides - metabolism; Phage-display; Protein Binding; Calpain; Calcium; Peptide; Phage-display
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2005.06.036

Calpains are calcium- and thiol-dependent proteases that cleave a variety of intracellular substrates. Overactivation of the calpains has been implicated in a number of diseases and conditions such as ischemic stroke indicating a need for the development of calpain inhibitors. A major problem with current calpain inhibitors has been specific targeting to calpain. To identify highly specific calpain interacting peptides, we developed a peptide-phage library screening method based on the calcium-dependent conformation change associated with calpain activation. A phage-peptide library representing greater than 2 billion expressed 12-mers was incubated with calpain I in the presence of calcium. The calcium-dependent bound phage was then eluted by addition of EGTA. After four rounds of selection we found a conserved 5-mer sequence represented by LSEAL. Synthetic LSEAL inhibited τ-calpain interaction and in vitro proteolysis of τ- and α-synuclein by calpains. Deletion of the portion of the τ protein containing a homologous sequence to LSEAL resulted in decreased calpain-mediated τ degradation. These data suggest that these peptides may represent novel calpastatin mimetics.