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Abstract

Correlations between amide proton temperature coefficients (deltasigmaHN/deltaT) and hydrogen bonds were investigated for a data set of 793 amides derived from 14 proteins. For amide protons showing temperature gradients more positive than -4.6 ppb/K there is a hydrogen bond predictivity value exceeding 85%. It increases to over 93% for amides within the range between -4 and -1 ppb/K. Detailed analysis shows an inverse proportionality between amide proton temperature coefficients and hydrogen bond lengths. Furthermore, for hydrogen bonds of similar bond lengths, values of temperature gradients in alpha-helices are on average I ppb/K more negative than in beta-sheets. In consequence. a number of amide protons in alpha-helices involved in hydrogen bonds shorter than 2 A show deltasigmaHN/deltaT < -4.6 ppb/K. Due to longer hydrogen bonds, 90% of amides in 3(10) helices and 98% in beta-turns have temperature coefficients more positive than -4.6ppb/K. Ring current effect also significantly influences temperature coefficients of amide protons. In seven out of eight cases non-hydrogen bonded amides strongly deshielded by neighboring aromatic rings show temperature coefficients more positive than -2 ppb/K. In general, amide proton temperature gradients do not change with pH unless they correspond to conformational changes. Three examples of pH dependent equilibrium showing hydrogen bond formation at higher pH were found. In conclusion, amide proton temperature coefficients offer an attractive and simple way to confirm existence of hydrogen bonds in NMR determined structures.

Structure of the R3/I5 Chimeric Relaxin Peptide, a Selective GPCR135 and GPCR142 Agonist

“…Amide protons involved in hydrogen bonds are protected from the solvent and their chemical shifts are less affected by changes in temperature. Amide protons with a ⌬␦ HN /⌬T Ͼ Ϫ4.6 ppb/K are likely to be involved in hydrogen bonds (28). The spectral data were calibrated to internal 2,2-dimethyl-2-silapentanesulfonic acid at 0.0 ppm.…”

Effect of Temperature and the F27W Mutation on the Ca2+ Activated Structural Transition of Trout Cardiac Troponin C

“…Many of the residues could not be assigned in the apo state, making it especially difficult In the one-Ca 2+ state, three residues had positive temperature coefficients (I26, D67, and V79), which can be caused by local structure changes between the two temperatures. I26 and V79 are both located close to aromatic residues, and changes in the distance between the amide and the aromatic rings have been suggested as a mechanism to cause positive temperature coefficients (19).…”

The key position: influence of staple location on constrained peptide conformation and binding

“…NMR analysis also revealed the aspartate linker residues had unusually large and negative NH temperature coefficients, despite being consistently hydrogen bonded in the calculated structures. Previous reports suggest that both NH temperature coefficients and NH secondary shifts are influenced by hydrogen bond length 22,27 . Shorter hydrogen bonds (< 2 Å) are associated with downfield shifted NH resonances and temperature coefficients less than -4ppb/K, while bonds longer than 2Å are shifted upfield and have temperature coefficients greater than -4ppb/K.…”

“…Scrutiny of the calculated lactam structures confirms all calculated aspartate linker NH hydrogen bonds were less than 2Å, however other hydrogen bonds were also found to have distances in this range (data not shown). It is possible that the presence of the lactam amide functional group might be influencing residue i+4 secondary shifts and temperature coefficients, however the downfield shifted NH suggests a deshielding effect of the lactam, while the unusually large and negative NH temperature coefficient is more consistent with a shielding effect from this group 27 . Similar effects on linker αH and temperature coefficients were found for constrained peptides studied by Hoang et al 28 .…”