Following conjugation with glutathione, xenobiotics are converted into cysteinylglycine conjugates, cysteine conjugates, and, finally, mercapturic acids. The structural factors determining the activities of dipeptidases for the metabolism of toxicologically-relevant cysteinylglycine conjugates are not well understood. I purified porcine kidney cortex membrane dipeptidase (MDP) to homogeneity, via phosphatidylinositol-specific phospholipase C-mediated cleavage of the protein’s membrane anchor and cilastatin affinity chromatography. The homodimeric structure of the MDP protein was confirmed by mass spectrometry. To test the enzyme activity of purified MDP, the cysteinylglycine conjugates of 1-(chloromethyl)naphthalene, 4-nitrobenzyl chloride, and 1-chloro-2,4-dinitrobenzene were synthesized and HPLC separation methods for their quantitation were developed. MDP catalyzed the hydrolysis of all three conjugates, but the rate of this activity was strongly dependent on the nature of the substituent on the cysteine sulfur atom.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OGU.10214/3897 |
| Date | 31 August 2012 |
| Creators | Poon, James |
| Contributors | Josephy, P. David |
| 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 | Thesis |
Page generated in 0.0018 seconds