title: Longitudinal relaxation optimized amide1H-CEST experiments for studying slow chemical exchange processes in fully protonated proteins.
abstract: Chemical Exchange Saturation Transfer (CEST) experiments are increasingly used to study slow timescale exchange processes in biomolecules. Although15N- and13C-CEST have been the approaches of choice, the development of spin state selective1H-CEST pulse sequences that separate the effects of chemical and dipolar exchange [T. Yuwen, A. Sekhar and L. E. Kay, Angew Chem Int Ed Engl 2016 doi: 10.1002/anie.201610759 (Yuwen et al. 2017)] significantly increases the utility of1H-based experiments. Pulse schemes have been described previously for studies of highly deuterated proteins. We present here longitudinal-relaxation optimized amide1H-CEST experiments for probing chemical exchange in protonated proteins. Applications involving a pair of proteins are presented establishing that accurate1H chemical shifts of sparsely populated conformers can be obtained from simple analyses of1H-CEST profiles. A discussion of the inherent differences between15N-/13C- and1H-CEST experiments is presented, leading to an optimal strategy for recording1H-CEST experiments.
authors.affiliation: Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada.
authors.forename: Tairan
authors.initials: T
authors.lastname: Yuwen
authors.affiliation: Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, ON, Canada. kay@pound.med.utoronto.ca.|Hospital for Sick Children, Program in Molecular Structure and Function, Toronto, ON, Canada. kay@pound.med.utoronto.ca.
authors.forename: Lewis E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D000577:Amides / Q000737:chemistry; D002247:Carbon Isotopes; D041961:Deuterium Exchange Measurement; D006801:Humans; D007553:Isotope Labeling; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D035321:Telomeric Repeat Binding Protein 1 / Q000737:chemistry*
chemical_list: D000577:Amides; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011506:Proteins; D035321:Telomeric Repeat Binding Protein 1
keywords: 1H chemical exchange saturation transfer; Protein dynamics; Rare conformational states; Slow exchange