title: 13C and 15N spectral editing inside histidine imidazole ring through solid-state NMR spectroscopy.
abstract: Histidine usually exists in three different forms (including biprotonated species, neutral τ and π tautomers) at physiological pH in biological systems. The different protonation and tautomerization states of histidine can be characteristically determined by (13)C and (15)N chemical shifts of imidazole ring. In this work, solid-state NMR techniques were developed for spectral editing of (13)C and (15)N sites in histidine imidazole ring, which provides a benchmark to distinguish the existing forms of histidine. The selections of (13)Cγ, (13)Cδ2, (15)Nδ1, and (15)Nε2 sites were successfully achieved based on one-bond homo- and hetero-nuclear dipole interactions. Moreover, it was demonstrated that (1)H, (13)C, and (15) chemical shifts were roughly linearly correlated with the corresponding atomic charge in histidine imidazole ring by theoretical calculations. Accordingly, the (1)H, (13)C and (15)N chemical shifts variation in different protonation and tautomerization states could be ascribed to the atomic charge change due to proton transfer in biological process.
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan 430071, China. lishenhui@wipm.ac.cn
authors.forename: Shenhui
authors.initials: S
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Yongchao
authors.initials: Y
authors.lastname: Su
authors.forename: Bin
authors.initials: B
authors.lastname: Han
authors.forename: Feng
authors.initials: F
authors.lastname: Deng
mesh_terms: D006639:Histidine / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D011522:Protons
chemical_list: D007093:Imidazoles; D011522:Protons; D006639:Histidine; C029899:imidazole
keywords: DFT calculation; Histidine; Solid state NMR; Spectral editing