Two kinds of affinity chromatography, CDP-choline- and CTP-Sepharose 4B, were investigated for purification of the cytosolic CTP:phosphocholine cytidylyltransferase from rat liver. The enzyme did not show strong affinity for the CDP-choline Sepharose resin, but bound to the CTP-Sepharose column in the presence of 14 mM magnesium acetate. The combination of CTP affinity chromatography
with ion-exchange techniques provided about 70-fold purification of the cytosolic enzyme with a specific activity of about 90 units per milligram protein.
The influence of diphenylsulfone compounds on the synthesis
of phosphatidylcholine by the CDP-choline pathway was examined in
isolated rat hepatocytes and HeLa cells. The administration of
the sulfones (100 ug/ml), except dapsone, to HeLa cells inhibited
the total [methyl-³H]choline incorporation into the cells, but did not change the rate of conversion of choline to phosphatidylcholine.
The addition of the sulfones (100 ug/ml) to rat hepatocytes
did not inhibit the biosynthesis of phosphatidylcholine and choline metabolism.
The effect of vasopressin on the distribution of cytidylyl-transferase between cytosol and microsomes in rat hepatocytes was also investigated. The digitonin-mediated release of cytosolic cytidylyltransferase was reduced from the cells treated with vasopressin (5-20 nM) , while the enhanced rate of incorporation of [methyl-³H]choline into phosphatidylcholine was not observed. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/25073 |
| Date | January 1985 |
| Creators | Yao, Zemin |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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