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Title: Isoenzymes in different tissues and cultured cells in genetically determined human diseases
Author: Broadhead, D. M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1979
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The component forms of three hydrolytic enzymes, N-acetyl-P-D-hexosaminidase, a-D-glucosidase and S-D-glucosidase, were studied in certain tissues, cultured cells and fluids. The possibility that hexosaminidases A and B had a common subunit and differed by a subunit, which was also a constituent of the neutral component, hexosaminidase C, was investigated and it was found that hexosaminidase C was unlikely to be related to either of the two major hexosaminidase components. The properties of another minor component, hexosaminidase S, suggested that this may contain the unique subunit of hexosaminidase A. In addition to the a-glucosidase component deficient in Pompe's disease, three other apparently genetically unrelated components were identified. One of these, which had a neutral pH optimum and little activity at pH 4.0 occurred in most tissues, but was very labile. The others, one found in amniotic fluid and the other in kidney and leucocytes, although having neutral pH optima, had considerable activity at pH 4.0, thereby interfering with the diagnosis of Pompe's disease. The enzyme found to be deficient in Gaucher's disease was associated with the P-glucosidase activity eluting in the void volume of Sephadex G-150. Two other more neutral components were detected, one of which was also in the void volume and the other, only present in some livers and in spleen, was of lower molecular weight. Neither of these components was deficient in either of the two cases of neuronopathic Gaucher's disease studied. Methods were developed for detecting enzyme deficiencies when there were other components with hydrolytic activity towards the artificial substrate in the tissue being used. The IEAE-cellulose batch method was the most useful for detecting hexosaminidase A. Interfering a-glucosidase components were removed by isoelectric precipitation at pH 5.0 or the activity of the acid a-glucosidase was determined indirectly using equations derived on the basis of the relative susceptibility of components to inhibitors. Non-specific O-glucosidases residual in Gaucher tissues could be removed by preincubation in 50RK-sodium chloride buffered at pH 4.0.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available