Bjelke, Jais R3; Christensen, Jesper4; Nielsen, Per F3; Branner, Sven3; Kanstrup, Anders B3; Wagtmann, Nicolai3; Rasmussen, Hanne B3
1 Helin Group, BRIC Research Groups, BRIC, Københavns Universitet2 BRIC, BRIC, Københavns Universitet3 unknown4 Helin Group, BRIC Research Groups, BRIC, Københavns Universitet
Dipeptidyl peptidases 8 and 9 have been identified as gene members of the S9b family of dipeptidyl peptidases. In the present paper, we report the characterization of recombinant dipeptidyl peptidases 8 and 9 using the baculovirus expression system. We have found that only the full-length variants of the two proteins can be expressed as active peptidases, which are 882 and 892 amino acids in length for dipeptidyl peptidase 8 and 9 respectively. We show further that the purified proteins are active dimers and that they show similar Michaelis-Menten kinetics and substrate specificity. Both cleave the peptide hormones glucagon-like peptide-1, glucagon-like peptide-2, neuropeptide Y and peptide YY with marked kinetic differences compared with dipeptidyl peptidase IV. Inhibition of dipeptidyl peptidases IV, 8 and 9 using the well-known dipeptidyl peptidase IV inhibitor valine pyrrolidide resulted in similar K(i) values, indicating that this inhibitor is non-selective for any of the three dipeptidyl peptidases.
Biochemical Journal, 2006, Vol 396, Issue 2, p. 391-9