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Title: Structural studies on two lipocalins
Author: de Morais Cabral, João Henrique Resende de Oliveira
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1993
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The number of proteins being included in the lipocalin structural family has been steadily increasing since the solution of the structures of beta-lactoglobulin and retinol-binding protein. The family now comprises some 21 proteins and these come from many different sources and display a variety of characteristics. The work described here focused on two of those proteins, beta-lactoglobulin (Blg) and apolipoprotein D (apo D). The structure of bovine beta-lactoglobulin from the trigonal crystals grown at pH 7.8, space group P3221, presents several aspects that are in disagreement with previous work, in particular the positioning of the bound retinol in the surface of the protein and the observation that the protein was in its monomeric form. We have checked these findings independently by extending the resolution of a 6 AA x-ray structure. A 3.0 AA model is now available though still in the refinement stages. Not surprisingly it was found that the protein is indeed in the dimeric form and that the arrangement of the dimer is very similar to the one found in BlgY (orthorhombic crystal form), the other independently determined structure. Changes were observed in the threading of the sequence, in particular between residues 75 and 32 where movements of as much as five residues are found, and in the C-terminus between 141 and 150 where a shift of one residue is observed along a β-strand. These changes result in an overall increase of the hydrophobilcity of the pocket. In parallel, cocrystallization of Blg with a variety of ligands has been successful in at least one case where density is evident in the binding cavity. Human apolipoprotein D is present in the fluid of cysts formed during gross-cystic-disease, which is the most common breast disease in premenopausal women, and is a potential biological marker for breast cancer. The protein is found as well, associated with the lipoproteic system in the blood and is produced in high amounts in regenerating rat peripherial nerves.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available