Lipoprotein in association with thyroglobulin

Ballany, John M (1976) Lipoprotein in association with thyroglobulin. PhD thesis, University of Glasgow.

Abstract

Purified thyroglobulin, both commercially available and personally prepared by ammonium sulphate precipitation, when fractionated on sephadex C200 shows only one peak whereas on sepharose 6B three peaks are found, two of which were examined further and designated peak 1 and peak 2. Both peaks are large molecular weight molecules. Ultracentrifugation, on sucrose gradients, of purified peak 1 and peak 2 showed peak 2 to behave similarly to 196 thyroglobulin. Peak 1, however, was not found on these gradients, which suggests that it is a low density molecule. Polyacrylamide gel and agarese gel electrophoreasis show peak 1 to have different electropheratic mobility and to be composed of different components from peak 2. Iso-electric focussing showed peak 1 to have a lower iso-electric point that peak 2. Amino acid analysis showed significant differences between the two peaks, which is further verified by values for protein bound iodine, peak 1 having 20% of the iodine content of peak 2. The absorbance spectrum between 230nm and 300nm proves that both peaks are composed of different substances. Peak 2 was shown to be 19s thyroglobulin. Peak 1 contained triglcerids and cholesterol in addition to amino acids and was therefore considered to be a larger molecular weight very low density lipoprotein of the pre-beta type. Time course of radioactive iodine labelling (125I, 131I) of both peaks by intraperitoneal injection using iodine deficient, normal iodine, and iodine enbanced rats showed that peak 2 actively trapped trapped iodine but peak 1 appeared to be passively labelled. Further time course labelling experiments using an inhibitor of iodine organification verified that peak 1 was passively labelled but appeared to be iodinated from the recycling of iodine from deiodinated thyroid hormones. Since the lipoprotein which constitutes peak 1 contains significant stable iodine, this may be the second iodine pool of the thyroid gland.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: J A Thomson
• Keywords: Molecular biology
• Date of Award: 1976
• Depositing User: Enlighten Team
• Unique ID: glathesis:1976-72954
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72954