title: Combination of heteronuclear 1H-15N and 1H-13C three-dimensional nuclear magnetic resonance experiments for amide-directed sequential assignment in larger proteins.
abstract: A new strategy for the sequential assignment of backbone proton resonances in larger proteins involving a unique combination of four types of heteronuclear three-dimensional (3D) NMR spectroscopies is reported. This method relies on the uniform labeling of amide nitrogens with 15N and of alpha-carbons with 13C. Heteronuclear 1H-15N TOCSY-HMQC and NOESY-HMQC experiments can reveal connections between cross-peaks arising from the NHi-C alpha Hi-1 and NHi-C alpha Hi connectivities in the finger-print region in in general. They also specifically reveal the sequential amide-amide connectivities among the amide cross-peaks for the alpha-helices. Heteronuclear 1H-13C HMQC-TOCSY and HMQC-NOESY experiments can reveal connections between cross-peaks arising from the NHi-C alpha Hi and NHi+1-C alpha Hi connectivities in the finger-print region in general. The combination of the two sets of results reveals the complete unambiguous sequential connection of cross-peaks for the proton resonances in the peptide backbone. The application of the new strategy is reported for a protein, ribonuclease H, with a molecular weight of 17.6 kDa.
authors.affiliation: Biometrology Lab, JEOL Ltd., Tokyo.
authors.forename: K
authors.initials: K
authors.lastname: Nagayama
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: S
authors.initials: S
authors.lastname: Kanaya
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000596:Amino Acids / Q000032:analysis; D004722:Endoribonucleases / Q000032:analysis; D004926:Escherichia coli / Q000032:analysis; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D010449:Peptide Mapping; D011506:Proteins / Q000032:analysis*; D016914:Ribonuclease H; D012260:Ribonucleases / Q000032:analysis
chemical_list: D000596:Amino Acids; D011506:Proteins; D004722:Endoribonucleases; D012260:Ribonucleases; D016914:Ribonuclease H