Structure/function and conformation/activity relationships for biologically significant peptides.
Item
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Title
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Structure/function and conformation/activity relationships for biologically significant peptides.
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Identifier
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AAI9218279
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identifier
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9218279
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Creator
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Tallon, Michael Anthony.
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Contributor
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Adviser: Fred Naider
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Date
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1992
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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 | Biophysics, Medical | Health Sciences, Pharmacy
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Abstract
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Peptides corresponding to putative loop regions 107-125, 191-206, and 350-372 for the {dollar}\alpha{dollar}-factor receptor of the yeast Saccharomyces cerevisiae were synthesized by solid phase methods in purified yields ranging from 15 to 44% of theoretical. These peptides were greater than 98% homogeneous as judged by gradient reversed phase HPLC, and were characterized by either FAB-MS, amino acid analysis, or 200 MHz {dollar}\sp1{dollar}H-NMR spectroscopy. The synthetic peptides were used to generate polyclonal antisera which will be utilized as topological probes for the {dollar}\alpha{dollar}-factor receptor in future studies.;Peptide based probes for the {dollar}\alpha{dollar}-factor binding site within the STE-2 receptor were synthesized by incorporation of either a biotin, fluorescein, or the Bolton Hunter group into the (Nle{dollar}\sp{12}{dollar}) -{dollar}\alpha{dollar}-factor pheromone, or into the tetradecapeptide analog, (Lys{dollar}\sp{lcub}-1{rcub}{dollar}, Nle{dollar}\sp{12}{dollar}) -{dollar}\alpha{dollar}-factor. All of these peptides are within one order of magnitude as active as the native pheromone, and therefore represent a class of reagents that will be useful in identifying the pheromone binding site.;In addition to the synthesis of receptor probes, detailed conformational analyses on cyclo{dollar}\sp{lcub}7,10{rcub}{dollar} (Nle{dollar}\sp{12}{dollar}) -{dollar}\alpha{dollar}-factor and on a biologically active analog of the mammalian peptide hormone Substance P, (pGlu{dollar}\sp6{dollar}-Phe-NMePhe{dollar}\sp8{dollar}-Aib{dollar}\sp9{dollar}-Leu-Met{dollar}\sp{11}{dollar}-NH{dollar}\sb2{dollar}) SP{dollar}\sp{lcub}6-11{rcub}{dollar}, were performed in DMSO-d{dollar}\sb6{dollar} at 25{dollar}\sp\circ{dollar}C, utilizing 2D NMR techniques. The results indicate that a mixture of type I and type II {dollar}\beta{dollar}-turns, spanning residues 7-10 in the cyclic {dollar}\alpha{dollar}-factor, is present in DMSO. Long range interactions were also observed, indicating the ends of this molecule are in close proximity. The NMR results on the NK3 selective Substance P analog indicate that (pGlu{dollar}\sp6{dollar}, NMePhe{dollar}\sp8{dollar}, Aib{dollar}\sp9{dollar}) SP{dollar}\sp{lcub}6-11{rcub}{dollar} exhibits cis/trans isomerism about the Phe{dollar}\sp7{dollar}-NMePhe{dollar}\sp8{dollar} peptide bond. This results in a 60/40 mixture of cis and trans forms of this hexapeptide in DMSO at 25{dollar}\sp\circ{dollar}C. Long range interactions were observed which indicate that both the cis and trans isomers are bent in solution. In each molecule, the amide and terminal carboxamide of methionine{dollar}\sp{11}{dollar} are hydrogen bonded. Our results suggest that the Substance P analog is conformationally restricted and that consecutive C{dollar}\sb7{dollar} conformations may span residues Aib{dollar}\sp9{dollar}-Leu-Met{dollar}\sp{11}{dollar}-NH{dollar}\sb2{dollar}.
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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.
