Structure of the active 27‐residue fragment of human calpastatin

Publisher Website
Google Scholar
Abstract
A synthetic 27‐residue peptide corresponding to exon 1B of the endogenous inhibitor calpastatin contains a well‐conserved region and has an ability to inhibit the cysteine endopeptidase calpain specifically. We examined the solution structure of this peptide in DMSO‐d6 by two‐dimensional 1H NMR spectroscopy. Although regular secondary structures such as α‐helix and β‐sheet were not found, the region from Ile18 to Arg23 formed a well‐defined structure with a type I β‐turn. This region coincided well with the highly conserved region of calpastatin. The result strongly suggests that this turn structure is essential for the inhibitory activity of calpastatin.