New Zealand Journal of Agricultural Research abstracts

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A functional comparison of ovine and porcine chymotrypsins

Keryn Dallas Johnson^1,2,*
Sue Marshall^1,2,†
Alan Clark^1,‡

¹School of Biological Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand
²Dairy Meats New Zealand Ltd
Eltham, New Zealand

*Present address: Industrial Research Limited, P.O. Box 31 310, Lower Hutt, New Zealand.
^†Present address: Crop & Food Research, P.O. Box 5114, Port Nelson, Nelson, New Zealand.
^‡Author for correspondence. alan.clark@vuw.ac.nz

Abstract  Chymotrypsin was isolated from ovine and porcine pancreas by affinity chromatography on immobilised 4-phenylbutylamine. The apparent molecular weights of the two proteins were estimated by SDS PAGE to be 25.7 and 27.3 kD respectively. Specific activities for ovine and porcine chymotrypsins (OC and PC) were 32.8 and 31.2 µmol/min per mg, respectively, at pH 8.5 and 25°C using 0.1 mM N-succinyl-Ala-Ala-Pro-Phe-pNA (SAAPFpNA) as substrate. Values of the Michaelis constants for ovine and porcine chymotrypsins with SAAPFpNA were comparable at pH 8.0 and at temperatures between 20 and 45ºC, as were the k_cat values. Both enzymes were stable under acidic conditions but were susceptible to thermal denaturation above 45°C. Hydrolysis of lysozyme and casein by ovine or porcine chymotrypsin yielded very similar fragmentation profiles as determined by RP-HPLC.

Keywords  affinity chromatography; ovine; pancreatic; porcine; purification; chymotrypsin, protease

A04048; Received 21 May 2004; accepted 24 April 2005; Online publication date 4 August 2005
New Zealand Journal of Agricultural Research, 2005, Vol. 48: 311–319
0028–8233/05/4803–0311 © The Royal Society of New Zealand 2005

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