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Synthesis of Δ E Phe‐containing tripeptide via photoisomerization and its conformation in solution

Synthesis of Δ E Phe‐containing tripeptide via photoisomerization and its conformation in solution A new synthetic route to (E)‐β‐phenyl‐α,β‐dehydroalanine (ΔEPhe)‐containing peptide was presented via photochemical isomerization of the corresponding (Z)‐β‐phenyl‐α,β‐dehydroalanine (ΔZPhe)‐containing peptide. By applying this method to Boc–Ala–ΔZPhe–Val–OMe (Z‐I: Boc, t‐butoxycarbonyl; OMe, methoxy), Boc–Ala–ΔEPhe–Val–OMe (E‐I) was obtained. The identification of peptide E‐I was evidenced by 1H‐nmr, 13C‐nmr, and uv absorption spectroscopy, elemental analysis, and hydrogenation. The conformation of peptide E‐Iin CDCl3 was investigated by 1H‐nmr spectroscopy (solvent dependence of NH chemical shift and difference nuclear Overhauser effect). Interestingly, peptide E‐I differed from peptide Z‐I in the hydrogen‐bonding mode. Namely, for peptide Z‐I, only Val NH participates in intramolecular hydrogen bonding, which leads to a type II β‐turn conformation supported by hydrogen bonding between CO(Boc) and NH(Val). On the other hand, for peptide E‐I, two NHs, ΔE Phe NH and Val NH, participate in intramolecular hydrogen bonding. In both peptides, a remarkable NOE (∼11–13%) was observed for Ala Cα H–ΔPhe NH pair. Based on the nmr data and conformational energy calculation, it should be concluded that peptide E‐I takes two consecutive γ‐turn conformations supported by hydrogen bonding between CO(Boc) and NH(ΔEPhe), and between CO(Ala) and NH(Val) as its plausible conformation. © 2000 John Wiley & Sons, Inc. Biopoly 53: 484–496, 2000 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Biopolymers Wiley

Synthesis of Δ E Phe‐containing tripeptide via photoisomerization and its conformation in solution

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Publisher
Wiley
Copyright
Copyright © 2000 John Wiley & Sons, Inc.
ISSN
0006-3525
eISSN
1097-0282
DOI
10.1002/(SICI)1097-0282(200005)53:6<484::AID-BIP5>3.3.CO;2-1
Publisher site
See Article on Publisher Site

Abstract

A new synthetic route to (E)‐β‐phenyl‐α,β‐dehydroalanine (ΔEPhe)‐containing peptide was presented via photochemical isomerization of the corresponding (Z)‐β‐phenyl‐α,β‐dehydroalanine (ΔZPhe)‐containing peptide. By applying this method to Boc–Ala–ΔZPhe–Val–OMe (Z‐I: Boc, t‐butoxycarbonyl; OMe, methoxy), Boc–Ala–ΔEPhe–Val–OMe (E‐I) was obtained. The identification of peptide E‐I was evidenced by 1H‐nmr, 13C‐nmr, and uv absorption spectroscopy, elemental analysis, and hydrogenation. The conformation of peptide E‐Iin CDCl3 was investigated by 1H‐nmr spectroscopy (solvent dependence of NH chemical shift and difference nuclear Overhauser effect). Interestingly, peptide E‐I differed from peptide Z‐I in the hydrogen‐bonding mode. Namely, for peptide Z‐I, only Val NH participates in intramolecular hydrogen bonding, which leads to a type II β‐turn conformation supported by hydrogen bonding between CO(Boc) and NH(Val). On the other hand, for peptide E‐I, two NHs, ΔE Phe NH and Val NH, participate in intramolecular hydrogen bonding. In both peptides, a remarkable NOE (∼11–13%) was observed for Ala Cα H–ΔPhe NH pair. Based on the nmr data and conformational energy calculation, it should be concluded that peptide E‐I takes two consecutive γ‐turn conformations supported by hydrogen bonding between CO(Boc) and NH(ΔEPhe), and between CO(Ala) and NH(Val) as its plausible conformation. © 2000 John Wiley & Sons, Inc. Biopoly 53: 484–496, 2000

Journal

BiopolymersWiley

Published: May 1, 2000

Keywords: synthesis of Δ E Phe‐containing tripeptide; Δ Z Phe–Δ E Phe photoisomerization; conformational analysis of Δ E Phe‐tripeptide; 1 H‐nmr spectroscopy; conformational energy calculation; consecutive γ‐turn conformation

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