Journal: Biochemistry

Article Title: Distinguishing Different Hydrogen-Bonded Helices in Proteins by Efficient 1 H-Detected Three-Dimensional Solid-State NMR

doi: 10.1021/acs.biochem.3c00589

Figure Lengend Snippet: Diagrams of NMR pulse sequences used in this work and some of the key timing parameters. (a) 2D hCOH experiment. A Cα-selective 180° pulse in the middle of t1 suppress CO-Cα J coupling whereas two selective 13C 180° pulses before t1 suppress the Bloch-Siegert shift. (b) 3D hCOhNH experiment for identifying CO - HN contacts. Chemical-shift encoded 13CO magnetization is transferred to amide protons, whose identities are revealed by 15N and 1H chemical shifts. (c) 3D hCONH experiment for resonance assignment. The CO magnetization is transferred to its directly bonded 15N by CP. (d) 1D 13C spectra of the three experiments. The hCOhNH experiment has ~25% of the efficiency of the hCOH experiment.

Article Snippet: Additional figures of 3D hCOhNH strips of ETM, the 3 10 helix distribution in the 30 lowest-energy structure of ETM, and 2D hCOH spectra measured with different CP contact times; the Bruker hCOhNH pulse program.

Techniques:

Journal: Biochemistry

Article Title: Distinguishing Different Hydrogen-Bonded Helices in Proteins by Efficient 1 H-Detected Three-Dimensional Solid-State NMR

doi: 10.1021/acs.biochem.3c00589

Figure Lengend Snippet: 2D 1H-detected spectra of membrane-bound ETM, prepared at pH 4.5 with Ca2+ to give the open state (a-c) and at pH 7.5 (d-f) to give the closed state. (a) hNH spectrum of the open ETM. (b) hCO(N)H spectrum of open ETM, obtained from the 2D projection of the 3D hCONH spectrum. (c) hCOH spectrum measured with a CO-H CP contact time of 3.5 ms. For resolved HNi chemical shifts, the CO chemical shift of residue i-j (j = 0-5) are assigned. (d) hNH spectrum of the closed ETM. (e) hCO(N)H spectrum of the closed ETM, obtained from the 2D projection of the 3D hCONH spectrum. (f) hCOH spectrum, measured with a CO-H CP contact time of 3.5 ms.

Article Snippet: Additional figures of 3D hCOhNH strips of ETM, the 3 10 helix distribution in the 30 lowest-energy structure of ETM, and 2D hCOH spectra measured with different CP contact times; the Bruker hCOhNH pulse program.

Techniques: Membrane, Residue