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Solvent and thermal stability, and pH kinetics, of proline-specific dipeptidyl peptidase IV-like enzyme from bovine serum

Ruth, Deborah M. and Buckley, Seamus J. and O'Connor, Brendan and Ó'Fágáin, Ciarán (2007) Solvent and thermal stability, and pH kinetics, of proline-specific dipeptidyl peptidase IV-like enzyme from bovine serum. Enzyme and Microbial Technology, 41 (3). pp. 307-311. ISSN 0141-0229

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Abstract

Proline-specific dipeptidyl peptidase-like (DPP IV; EC 3.4.14.5) activity in bovine serum has attracted little attention despite its ready availability and the paucity of useful proline-cleaving enzymes. Bovine serum DPP IV-like peptidase is very tolerant of organic solvents, particularly acetonitrile: upon incubation for 1 h at room temperature in 70% acetonitrile, 47% dimethylformamide, 54% DMSO and 33% tetrahydrofuran (v/v concentrations) followed by dilution into the standard assay mixture, the enzyme retained half of its aqueous activity. As for thermal performance in aqueous buffer, its relative activity increased up to 50 ◦C. Upon thermoinactivation at 71 ◦C, pH 8.0 (samples removed periodically, cooled on ice, then assayed under optimal conditions), residual activities over short times fit a first-order decay with a k-value of 0.071±0.0034 min−1. Over longer times, residual activities fit to a double exponential decay with k1 and k2 values of 0.218±0.025 min−1 (46±4% of overall decay) and 0.040±0.002 min−1 (54±4% of overall decay), respectively. The enzyme’s solvent and thermal tolerances suggest that it may have potential for use as a biocatalyst in industry. Kinetic analysis with the fluorogenic substrate Gly-Pro-7-aminomethylcoumarin over a range of pH values indicated two pK values at 6.18±0.07 and at 9.70±0.50. We ascribe the lower value to the active site histidine; the higher may be due to the active site serine or to a free amino group in the substrate.

Item Type:Article (Published)
Refereed:Yes
Uncontrolled Keywords:dipeptidyl peptidase IV; bovine serum; solvent stability; thermal stability; pH kinetics
Subjects:Biological Sciences > Biotechnology
Biological Sciences > Enzymology
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Biotechnology
Research Initiatives and Centres > National Centre for Sensor Research (NCSR)
Publisher:Elsevier
Official URL:http://dx.doi.org/10.1016/j.enzmictec.2007.02.007
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
ID Code:77
Deposited On:26 Jun 2007 by DORAS Administrator. Last Modified 20 Oct 2014 15:43

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