Fish viscera are produced in large quantities in the fishing industry and represent a waste disposal and environmental pollution problem. However, this material is a rich source of trypsins that may have some unique properties, such as high molecular activity at low processing temperature, low thermostability, and high pH optimum/pH stability, for both basic research and industrial applications. The main objectives of this project were to extract, purify and characterize trypsin from the pyloric ceca of hoki (Macruronus novaezealandiae ), which is by far the most important commercial fish in New Zealand. / Trypsin was purified from the pyloric ceca of hoki by ammonium sulfate fractionation, followed by acetone fractionation and affinity chromatography on SBTI-Sepharose 4B. The purified extract was simultaneously desalted and concentrated by ultrafiltration, and then characterized using N-alpha-benzoyl-DL-arginine-p-nitroanilide (BAPNA) as substrate. The affinity fraction migrated as a signal band in SDS-PAGE gels as well as in isoelectric focusing gels. The molecular weight of the isolated trypsin was determined by SDS-PAGE to be approximately 26,000 Da, whereas the MALDI-TOF MS method of analysis indicated a molecular weight of 23,791 Da. The isoelectric point was determined as 6.5. / The kinetic properties, temperature, pH and inhibition effects on the activity of the purified trypsin were verified. On the basis of the kinetic properties, hoki trypsin showed better amidase activity than bovine trypsin. The hoki trypsin had alkaline pH optimum (pH 9.0) and was stable at a high pH. Hoki trypsin had a higher optimum temperature (60°C) and still had relative higher activity at lower temperature. On the other hand, hoki trypsin was unstable at higher temperature. The enzyme was inhibited by well known trypsin inhibitors (SBTI, aprotinin, benzamidine and PMSF). The N-terminal residues of hoki trypsin, IVGGQECVPNSQPFMASLNY, displayed considerable homology with other fish trypsins. Based on the above characteristics, it is suggested that the hoki enzyme is authentic trypsin with potential for use in food industry and related applications.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.99205 |
| Date | January 2006 |
| Creators | Shi, Changying, 1977- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Food Science and Agricultural Chemistry.) |
| Rights | © Changying Shi, 2006 |
| Relation | alephsysno: 002574303, proquestno: AAIMR28529, Theses scanned by UMI/ProQuest. |
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