Peptide-modified nanochannel system for carboxypeptidase B activity detection.

Carboxypeptidase B (CPB) is a protease that specifically hydrolyzes C-terminal alkaline amino acid of a peptide, which plays an important role in biological analysis. The activity and inhibition of CPB are significant for peptide sequencing and protein engineering. In this paper, a sensitive and easily-prepared nanochannel system was used to detect the activity of CPB. We assembled the peptides composing of alkaline amino acids into the nanochannels to detect the activity of CPB based on its hydrolysis characteristic. With CPB, the peptides would be cleaved, causing less blocking-effect on the ionic current through nanochannels. This system exhibited high sensitivity (detection limit of 0.01 U mL-1), wide linear range (0.01-10 U mL-1), and fast response (less than 10 s) for specific CPB detection. We also used the system to detect the effect of CPB inhibitors and detect in complex actual samples. The strategy exhibits effective analytical characteristics and it can be regarded as a hopeful prospect for the rapid diagnosis of patients with pancreatitis.