Measurement of Very Fast Exchange Rates of Individual Amide Protons in Proteins by NMR Spectroscopy

TY - JOUR

T1 - Measurement of Very Fast Exchange Rates of Individual Amide Protons in Proteins by NMR Spectroscopy

AU - Dass, Rupashree

AU - Corlianò, Enrico

AU - Mulder, Frans A.A.

N1 - Special Issue: BioNMR Spectroscopy

PY - 2019/1/21

Y1 - 2019/1/21

N2 - NMR spectroscopy is a pivotal technique to measure hydrogen exchange rates in proteins. However, currently available NMR methods to measure backbone exchange are limited to rates of up to a few per second. To raise this limit, we have developed an approach that is capable of measuring proton exchange rates up to approximately 104 s−1. Our method relies on the detection of signal loss due to the decorrelation of antiphase operators 2NxHz by exchange events that occur during a series of pi pulses on the 15N channel. In practice, signal attenuation was monitored in a series of 2D H(CACO)N spectra, recorded with varying pi-pulse spacing, and the exchange rate was obtained by numerical fitting to the evolution of the density matrix. The method was applied to the small calcium-binding protein Calbindin D9k, where exchange rates up to 600 s−1 were measured for amides, where no signal was detectable in 15N−1H HSQC spectra. A temperature variation study allowed us to determine apparent activation energies in the range 47–69 kJ mol−1 for these fast exchanging amide protons, consistent with hydroxide-catalyzed exchange.

AB - NMR spectroscopy is a pivotal technique to measure hydrogen exchange rates in proteins. However, currently available NMR methods to measure backbone exchange are limited to rates of up to a few per second. To raise this limit, we have developed an approach that is capable of measuring proton exchange rates up to approximately 104 s−1. Our method relies on the detection of signal loss due to the decorrelation of antiphase operators 2NxHz by exchange events that occur during a series of pi pulses on the 15N channel. In practice, signal attenuation was monitored in a series of 2D H(CACO)N spectra, recorded with varying pi-pulse spacing, and the exchange rate was obtained by numerical fitting to the evolution of the density matrix. The method was applied to the small calcium-binding protein Calbindin D9k, where exchange rates up to 600 s−1 were measured for amides, where no signal was detectable in 15N−1H HSQC spectra. A temperature variation study allowed us to determine apparent activation energies in the range 47–69 kJ mol−1 for these fast exchanging amide protons, consistent with hydroxide-catalyzed exchange.

KW - hydrogen exchange

KW - kinetics

KW - NMR spectroscopy

KW - protein folding

KW - spin−spin decorrelation

UR - http://www.scopus.com/inward/record.url?scp=85058803299&partnerID=8YFLogxK

U2 - 10.1002/cphc.201801044

DO - 10.1002/cphc.201801044

M3 - Journal article

C2 - 30422360

AN - SCOPUS:85058803299

SN - 1439-4235

VL - 20

SP - 231

EP - 235

JO - ChemPhysChem

JF - ChemPhysChem

IS - 2

ER -