This research was part-funded by grant aid under the Food Sub-Programme of the Operational Programme for Industrial Development which is administered by the Department of Agriculture, Food and Forestry and supported by national and EU funds. We thank Dr Kevin Bailey, Dept of Biochemistry, Faculty of Medicine, University of Nottingham, for mass spectrometry analysis.
Protease Activities in Raw Milk Determined Using a Synthetic Heptapeptide Substrate
Article first published online: 20 JUL 2006
Journal of Food Science
Volume 64, Issue 4, pages 606–611, July 1999
How to Cite
O'Driscoll, B. M., Rattray, F. P., McSweeney, P. L. H. and Kelly, A. L. (1999), Protease Activities in Raw Milk Determined Using a Synthetic Heptapeptide Substrate. Journal of Food Science, 64: 606–611. doi: 10.1111/j.1365-2621.1999.tb15094.x
- Issue published online: 20 JUL 2006
- Article first published online: 20 JUL 2006
- MS received 8/17/98; revised 11/9/98; accepted 11/19/98.
- cathepsin D
A synthetic heptapeptide (H-Pro-Thr-Glu-Phe-[p-nitro-Phe]-Arg-Leu-OH) was used as substrate for detection and assay of cathepsin D in raw bovine milk. Cathepsin D produced a specific peptide, as detected by HPLC analysis of peaks for product and substrate. On incubation of acid wheys from milk samples with the substrate, three hydrolysis products were detected and bonds cleaved were identified by mass spectrometry. Inhibition studies were performed to identify enzymes responsible for the hydrolysis. One activity was cathepsin D and production of another peptide was inhibited by cysteine protease inhibitors, suggesting cysteine protease activity in milk.