Spectroscopic studies of the secondary structure of small peptides containing 4-(2-aminoethyl)-6-dibenzofuranpropanoic acid and synthesis of phosphomonoesters and phosphodiesters derived from the photohydrolysis of 2-methoxy-5-nitrophenyl substituted phosphotriesters /
Simple amides and peptides containing the
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1994.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=741965341&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Simple amides and peptides containing the conformationally restricted unnatural amino acids 4-(2- arninomethyl)-6-dibenzoftiranethanoic acid (2) and 4- amino-6-dibenzofuranmethanoic acid (3) were studied by NMR and FT-IR to ascertain their hydrogen bonding and 0- sheet nucleation capabilities as well as to compare them to the nucleator 4-(2-aminoethyl)-6- dibenzofuranpropanoic acid (1). Neither 2 nor 3 are effective P-sheet nucleators. Water soluble peptides containing I were studied using CD, I D- and 2D-NMR techniques to determine the mechanism by which residue 1 nucleates P-sheet structure formation. In solution, at pH 4-5, peptides containing hydrophobic residues or histidine in the i and i+3 positions exhibit a well- defined P-tum structure with the dibenzofuran ring of 1 adopting a perpendicular conformation with respect to the plane of the strands. The dibenzofuran portion of 1 interacts with either the hydrophobic side chains or the charged imidazole ring flanking it through a hydrophobic or 7E-cation-like interaction, thus forming a well- defined P-tum mimetic capable of propagating P-sheet structure through a portion of the attached peptide strands. This hydrophobic cluster also promotes the formation of a 15-membered ring hydrogen bonded conformation necessary for P-sheet nucleation. A potential photocleavable protecting group for the synthesis of phosphopeptides containing 1 was developed. Phosphotriesters composed of one or two 2-methoxy-5-nitrophenyl group(s) can be quantitatively photohydrolyzed in aqueous acetonitrile to yield the desired phosphodiester or phosphomonoester, respectively. Photohydrolysis occurs by attack of hydroxide at both the phosphoryl phoSDhorus and at the ipso-carbon in the triplet exited state of the 2-methoxy-5riitrophenyl substituted phosphoesters. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvi, 158 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |