Open AccessAn infrared study of 2 H‐bond variation in myoglobin revealed by high pressure
Author(s) -
TILLY Veronique,
SIRE Olivier,
ALPERT Bernard,
WONG Patrick T. T.
Publication year - 1992
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1992.tb16874.x
Subject(s) - myoglobin , chemistry , molecule , infrared , infrared spectroscopy , crystallography , fourier transform infrared spectroscopy , solvent , analytical chemistry (journal) , organic chemistry , chemical engineering , optics , physics , engineering
A high‐pressure Fourier‐transform infrared technique was used to probe the evolution of 2 H bonds inside the helical segments of myoglobin in relation to p 2 H, Tris concentration in the medium and iron‐ligand nature. The analysis was focused on changes in the conformation‐sensitive amide‐I′ band, reflecting the peptide C = O group stretching vibrations coupled to the in‐plane N‐ 2 H bending and C=N stretching modes. From data obtained under high pressure, the strength of 2 H bonds, inside the α‐helical segments of the protein at atmospheric pressure, is not simply a function of p 2 H and salt concentration. At low Tris concentration (50 mM), the strength of these 2 H bonds increases with p 2 H, whereas for a higher Tris concentration (100 mM) this strength is lower at p 2 H 7 than at p 2 H 6.0 or 8.5. It is also observed that the azidometmyoglobin molecule exhibits tighter intrahelical interactions and lower sensitivity to pressure than aquametmyoglobin. Information is also presented regarding interhelical interactions in relation to the solvent.