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Titolo:
Solvent dependence on the preference of helical screw sense: Effect of L-Leu residue second from N-terminal on screw sense in achiral peptide
Autore:
Inai, Y; Kurokawa, Y; Mirabayashi, T;
Indirizzi:
Nagoya Inst Technol, Grad Sch Engn, Dept Environm Technol & Urban Planning, Showa Ku, Nagoya, Aichi 4668555, Japan Nagoya Inst Technol Nagoya Aichi Japan 4668555 goya, Aichi 4668555, Japan
Titolo Testata:
MACROMOLECULES
fascicolo: 14, volume: 32, anno: 1999,
pagine: 4575 - 4581
SICI:
0024-9297(19990713)32:14<4575:SDOTPO>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
ALPHA-AMINOISOBUTYRIC-ACID; DELTA-Z-PHE; PENTAPEPTIDE SYSTEM (AIB)(4)/L-VAL; AMINO-ACIDS; CONFORMATIONAL-ANALYSIS; MOLECULAR-STRUCTURE; DEHYDROPHENYLALANINE RESIDUES; LINEAR OLIGOPEPTIDES; MAGNETIC-RESONANCE; CRYSTAL-STRUCTURE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Inai, Y Nagoya Inst Technol, Grad Sch Engn, Dept Environm Technol & Urban Planning, Showa Ku, Nagoya, Aichi 4668555, Japan Nagoya Inst Technol Nagoya Aichi Japan 4668555 chi 4668555, Japan
Citazione:
Y. Inai et al., "Solvent dependence on the preference of helical screw sense: Effect of L-Leu residue second from N-terminal on screw sense in achiral peptide", MACROMOLEC, 32(14), 1999, pp. 4575-4581

Abstract

To clarify which helical screw sense is preferred when one L-residue is introduced into the second position from N-terminal of an achiral helical segment, we prepared Boc-Aib-L-Leu-(Aib-Delta(Z)Phe)(2)-Aib-OMe (1: Boc = t-butoxycarbonyl; Aib = alpha-aminoisobutyric acid; Delta(Z)Phe = Z-dehydrophenylalanine; OMe = methoxy). Here the segment -(Aib-Delta(Z)Phe)(2)-Aib-OMe was used as an achiral backbone composed of two "enantiomeric" (left-/right-handed) helices. Peptide 1 was found to form a 3(10)-type helical conformation in chloroform, from FT IR (the position of amide I band) and H-1 NMR (difference nuclear Overhauser effect and solvent accessibility of NH resonances) measurements. Interestingly, CD patterns of peptide 1 changed with types of solvents: i.e., exciton couplets around 280 nm with a negative peak at longer wavelengths in chloroform and with a positive peak at longer wavelengths in methanol or in tetrahydrofuran. Consequently, the helical segmentprefers a right-handed screw sense in chloroform and a left-handed one in methanol or in tetrahydrofuran. Also, the preference of a screw sense changed reversibly, depending on chloroform-methanol mixtures of varying concentrations. Conformational energy calculation was carried out on acetyl-Aib-L-Leu-(Aib-Delta(Z)Phe)(2)-Aib-OMe, which was predicted to take both left- and right-handed helical conformations. The above experimental and theoretical results were compared with those of Boc-L-Leu-(Aib-Delta(Z)Phe)2-Aib-OMe,in which the N-terminal L-Leu residue induces a left-handed helical screw sense preferentially.

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Documento generato il 28/01/21 alle ore 07:41:34