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Title: The nature of Vicia faba α-galactosidases
Author: Sumar, Nazirabegum
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1983
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Two molecular forms I and II (separable by gel filtration) from mature Vicia faba seeds have been studied. The extractability of the enzymes and the in vitro conversion of the low MW form, II, to the larger oligomer, I has been examined over a range of salt concentrations. Specific and total activities of the preparations were high when strong salt solutions were used for extraction. It would appear that α-galactosidase I, in comparison with II, is best extracted from the seeds if solutions of high ionic strength are used. The effects of these salt solutions on the relative levels of the two forms have been investigated by gel filtration. Interpretation of the gel elution profiles obtained is, however, complicated by the in vitro conversion of form II to form I, which is favoured by high salt concentrations and some routine procedures in the purification of α-galactosidases, such as ammonium sulphate fractionation. The relationships between the multiple forms have been studied. α-galactosidase II can be resolved into enzymes II1 and II2 by CM-cellulose chromatography, a-Gal actosidases I, II1 and II2 have been highly purified. Form I (MW 160,000) is a tetramer of enzyme II2 as shown by SDS-PAGE. Immunological studies on the three forms have been carried out and the evidence suggests that they are structurally related, although forms I and II2 are more closely related than forms I and II. On hydrolysis,monosaccharides are released from the three purified enzymes, suggesting they are glycoproteins. The three α-galactosidases also agglutinate red blood cells indicating that they possess lectin activity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Molecular Biology