The 1H NMR spectrum of the title peptide, H-Leu-(Glu)5-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH, in 90% H2O/10% D2O was assigned by two-dimensional methods, and the displacement of the proton resonances upon addition of 2,2,2-trifluoroethanol (TFE) was followed. This permitted the assignment of the spectrum in 90% TFE/10% D2O. While the water conformation of the minigastrin analogue is random, the CD spectrum indicates that an ordered structure is present in TFE. Variable-temperature NMR data in this medium show that six amide protons have low temperature coefficients, two of the five Glu's, Trp, Nle, Asp, and Phe. These results were interpreted in terms of an a-helical stretch comprising the Leu and the five Glu residues and a 310-helix initiated by a b-turn at the sequence -Ala-Tyr-Gly-Trp-. Both CD and NMR data at different solvent compositions show two regions of conformational change, between 20 and 25% water and above 60% water.

Conformational Studies of Human Des-trp1,nle12-minigastrin In Water Trifluoroethanol Mixtures By H-1-nmr and Circular-dichroism

MAMMI, STEFANO;PEGGION, EVARISTO
1988

Abstract

The 1H NMR spectrum of the title peptide, H-Leu-(Glu)5-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH, in 90% H2O/10% D2O was assigned by two-dimensional methods, and the displacement of the proton resonances upon addition of 2,2,2-trifluoroethanol (TFE) was followed. This permitted the assignment of the spectrum in 90% TFE/10% D2O. While the water conformation of the minigastrin analogue is random, the CD spectrum indicates that an ordered structure is present in TFE. Variable-temperature NMR data in this medium show that six amide protons have low temperature coefficients, two of the five Glu's, Trp, Nle, Asp, and Phe. These results were interpreted in terms of an a-helical stretch comprising the Leu and the five Glu residues and a 310-helix initiated by a b-turn at the sequence -Ala-Tyr-Gly-Trp-. Both CD and NMR data at different solvent compositions show two regions of conformational change, between 20 and 25% water and above 60% water.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2510203
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