I. The application of phage display technology to trypanosome surface proteins. II. Studies of a thrombin inhibitor from green tea.
Item
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Title
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I. The application of phage display technology to trypanosome surface proteins. II. Studies of a thrombin inhibitor from green tea.
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Identifier
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AAI9969708
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identifier
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9969708
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Creator
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Lu, Jun.
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Contributor
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Adviser: Manfred Philipp
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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
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Abstract
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In part I of this study, living trypanosome cells, which cause African trypanosomiasis in human and in wild and domestic animals, have been used as a target to screen a phage display peptide library. Phage display technology is a method for the generation of molecular diversity and the screening for binding species of interest. This study demonstrates the first application of phage display technology to living African trypanosomes.;One strong binder (peptide 307) with an IC50 of 1 muM has been identified. Another peptide (peptide 608) has shown trypanolytic activity. The observed similar activities of both L- and D-type peptide 608 suggest that peptide 608 may attack the non-chiral lipid layers of cell membranes. The lytic activity of peptide 608 inhibited by wheat germ agglutinin indicates the presence of an interaction between peptide 608 and the flagellar pocket of trypanosomes. Peptide 307 also protected trypanosome cells from lysis by peptide 608, suggesting that these peptides bind at related sites on the trypanosomes. The predicted alpha-helix content in peptide 608 is 63%. The low hemolytic activity of peptide 608 also suggests that it may be possible to develop this peptide or others like it as anti-trypanosome drug candidates.;In part II of this study, extracts of green tea (Camellia sinenis ) were tested for their ability to inhibit thrombin, an enzyme important in blood coagulation. An active fraction was proven to be the major polyphenol of green tea, (-)-epigallocatechin gallate (EGCG). The chemical identity of the active fraction was determined by proton NMR, mass spectrometry, and by its chromatographic identity with an authentic sample. EGCG is a noncompetitive (Ki 80 muM) thrombin inhibitor that inhibits blood coagulation when measured by the Activated Partial Thromboplastin Time test, with an IC 50 of 600 muM.;Green tea is not likely to provide enough EGCG to cause a noticeable inhibition of blood coagulation. However, epidemiological studies have reported a reduced risk of coronary heart disease in subjects with a high intake of tea components. These results suggest that the anticoagulant activity of tea components should also be considered in interpreting such studies.
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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.
