proteaseresistant

Protease-resistant refers to the characteristic of a molecule—typically a protein or peptide—being resistant to proteolytic cleavage by proteases. In biochemistry and pharmacology, protease resistance is a key determinant of stability in biological environments and can extend the circulating half-life of therapeutic peptides or proteins.

Proteases cleave peptide bonds. Resistance arises from sequence features that avoid labile motifs, structural features such as rigid, well-folded conformations and cyclization, and chemical modifications including D-amino acids, N-methylation, and peptidomimetics.

Common strategies to increase protease resistance include cyclization (head-to-tail or side-chain), incorporation of D-amino acids at susceptible positions, backbone or side-chain modifications (N-methylation, peptidomimetics), stapled peptides, glycosylation, and PEGylation. These changes can be implemented in natural-expression systems or chemical synthesis and may be complemented by disulfide bonds or shielding motifs in some cases.

Applications of protease-resistant molecules are widespread. They include therapeutic peptides with longer in vivo half-lives, protease-resistant enzymes for industrial processes, antimicrobial peptides with improved stability in biological environments, and research probes. Trade-offs often accompany enhanced resistance, such as potential reductions in target affinity or specificity, altered folding or activity, possible immunogenicity, and higher production costs.

Measurement of protease resistance typically involves exposing the molecule to proteases or serum and monitoring the fraction remaining intact over time, using methods such as HPLC or mass spectrometry. The level of resistance is context-dependent, varying with the type of protease, pH, temperature, and the biological milieu.