Pressure dependence of side chain 1H and 15N-chemical shifts in the model peptides Ac-Gly-Gly-Xxx-Ala-NH2

• Published in: Journal of biomolecular NMR 2020-09, Vol.74 (8-9), p.381-399
• Main Authors: Beck Erlach, Markus, Koehler, Joerg, Munte, Claudia E., Kremer, Werner, Crusca, Edson, Kainosho, Masatsune, Kalbitzer, Hans Robert
• Format: Article
• Language: English
• Subjects: Biochemistry; Biological and Medical Physics; Biophysics; Physics; Physics and Astronomy; Spectroscopy/Spectrometry
• ISSN: 0925-2738; 1573-5001
• DOI: 10.1007/s10858-020-00326-w

For interpreting the pressure induced shifts of resonance lines of folded as well as unfolded proteins the availability of data from well-defined model systems is indispensable. Here, we report the pressure dependence of 1 H and 15 N chemical shifts of the side chain atoms in the protected tetrapeptides Ac-Gly-Gly-Xxx-Ala-NH 2 (Xxx is one of the 20 canonical amino acids) measured at 800 MHz proton frequency. As observed earlier for other nuclei the chemical shifts of the side chain nuclei have a nonlinear dependence on pressure in the range from 0.1 to 200 MPa. The pressure response is described by a second degree polynomial with the pressure coefficients B 1 and B 2 that are dependent on the atom type and type of amino acid studied. A number of resonances could be assigned stereospecifically including the 1 H and 15 N resonances of the guanidine group of arginine. In addition, stereoselectively isotope labeled SAIL amino acids were used to support the stereochemical assignments. The random-coil pressure coefficients are also dependent on the neighbor in the sequence as an analysis of the data shows. For H α and H N correction factors for different amino acids were derived. In addition, a simple correction of compression effects in thermodynamic analysis of structural transitions in proteins was derived on the basis of random-coil pressure coefficients.