Biochemical characterization of yeast cell adhesion proteins.
Item
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Title
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Biochemical characterization of yeast cell adhesion proteins.
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Identifier
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AAI9959246
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identifier
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9959246
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Creator
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Zhao, Hui.
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Contributor
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Adviser: Peter N. Lipke
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry | Biology, Molecular | Biophysics, General
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Abstract
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Studies in cell adhesion of lower organisms could provide information for understanding the more complex adhesion systems in higher organisms. In this work, sexual agglutination, the simplest yeast cell adhesion system, was the subject for studies of conformational properties of the cell adhesion molecule, alpha-agglutinin and its interaction with its binding ligand, a-agglutinin.;Circular dichroism (CD) and bioassays have been used to investigate the relationship between conformational and functional changes in a-agglutinin under different conditions. Parts of alpha-agglutinin reversibly switched conformation from beta-sheet to alpha-helix under conditions in which protein inactivation was reversible (pH +/- 8.5 or temperature ≤55°C). Model peptides derived from beta-turn-beta regions of alpha-agglutinin mimicked the behavior of the intact protein. Our results strongly implied that conformational switching occurred in some regions of the protein having high helical potential.;Real time interaction of the agglutinins has been characterized using isotopic labeling and Surface Plasmon Resonance ("SPR"). The interaction of the agglutinins had high affinity and a slow dissociation rate. The proteins became more structured upon binding. Kinetic and CD studies suggested that conformational rearrangements of the agglutinins were involved in the high affinity interaction. Hydrophobic interactions at the interface of the protein complex stabilized the conformation of the proteins.;Point mutations in domain III of alpha-agglutinin reduced the secretion of alpha-agglutinin. Moreover, the mutated alpha-agglutinin was more sensitive to protease digestion. The purified mutated alpha-agglutinin, however, had similar structural and functional properties as that of wild type protein. Our results implied that the point mutations led to misfolding of alpha-agglutinin, so that the protein could not be secreted properly.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
