Two-dimensional /sup 1/H NMR study of human ubiquitin: a main chain directed assignment and structure analysis

Journal Article · Tue Nov 17 04:00:00 EST 1987 · Biochemistry; (United States)

OSTI ID:5435863

Di Stefano, D L; Wand, A J

The /sup 1/H resonances of human ubiquitin were studied by two-dimensional nuclear magnetic resonance techniques. A recently introduced assignment algorithm termed the main chain directed (MCD) assignment was applied. This approach relies on an ordered series of searches for prescribed patterns of connectivities in two-dimensional J-correlated and nuclear Overhauser effect spectra and centers on the dipolar interactions involving main-chain amide HN, ..cap alpha..-CH, and ..beta..-CH. Unlike the sequential assignment procedure, the MCD approach does not rest upon definition of side-chain J-coupled networks and is generally not sequential with the primary sequence of the protein. The various MCD patterns and the general algorithm are reiterated and applied to the analysis of human ubiquitin. With this algorithm, the vast majority of amino acid residue amide NH-C/sub ..cap alpha../H-C/sub ..beta../H J-coupled subspin systems could be associated with and aligned within units of secondary structure without any knowledge of the identity of the side chains. The MCD method is compared with sequential assignment method in some detail. The MCD method is highly amenable to automation. Human ubiquitin is found, at pH 5.8 and 30/sup 0/ C, to be composed of an extensive ..beta..-sheet structure involving five strands. Three of these strands form an antiparallel set sharing a common strand and have a parallel orientation to two antiparallel strands. Two helical segments were also observed. The largest, spanning 13 residues, shown dipolar interactions consistent with an ..cap alpha..-helix while the smaller 4-residue helical segment appears, on the basis of observed nuclear Overhauser effects, to be a 3/sub 10/ helix. Five classical tight turns could be demonstrated.

• Research Organization: Institute for Cancer Research, Philadelphia, PA
• OSTI ID: 5435863
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:23; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ANIMALS
BARYONS
CHEMICAL SHIFT
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MAGNETIC RESONANCE
MAMMALS
MAN
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC COMPOUNDS
PRIMATES
PROTEINS
PROTONS
RESONANCE
STRUCTURAL CHEMICAL ANALYSIS
VERTEBRATES