Bjelke, Jais R3; Christensen, Jesper5; 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, Faculty of Health and Medical Sciences, Københavns Universitet5 Helin Group, BRIC, Faculty of Health and Medical Sciences, 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