Details

Autor(en) / Beteiligte

• Dunkelberger, Emily B
• Woys, Ann Marie
• Zanni, Martin T

Titel

2D IR Cross Peaks Reveal Hydrogen–Deuterium Exchange with Single Residue Specificity

Ist Teil von

• The journal of physical chemistry. B, 2013-12, Vol.117 (49), p.15297-15305

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2013

Quelle

MEDLINE

Beschreibungen/Notizen

• A form of chemical exchange, hydrogen–deuterium exchange (HDX), has long been used as a method for studying the secondary and tertiary structure of peptides and proteins using mass spectrometry and NMR spectroscopy. Using two-dimensional infrared (2D IR) spectroscopy, we resolve cross peaks between the amide II band and a 13C18O isotope-labeled amide I band, which we show measures HDX with site-specific resolution. By rapidly scanning 2D IR spectra using mid-IR pulse shaping, we monitor the kinetics of HDX exchange on-the-fly. For the antimicrobial peptide ovispirin bound to membrane bilayers, we find that the amide II peak decays with a biexponential with rate constants of 0.54 ± 0.02 and 0.12 ± 0.01 min–1, which is a measure of the overall HDX in the peptide. The cross peaks between Ile-10-labeled ovispirin and the amide II mode, which specifically monitor HDX kinetics at Ile-10, decay with a single rate constant of 0.36 ± 0.1 min–1. Comparing this exchange rate to theoretically determined exchange rates of Ile-10 for ovispirin in a solution random coil configuration, the exchange rate at Ile-10 is at least 100 times slower, consistent with the known α-helix structure of ovispirin in bilayers. Because backbone isotope labels produce only a very small shift of the amide II band, site-specific HDX cannot be measured with FTIR spectroscopy, which is why 2D IR spectroscopy is needed for these measurements.