1H resonance assignments and secondary structure of the carbon monoxide complex of soybean leghemoglobin determined by homonuclear two-dimensional and three-dimensional NMR spectroscopy. 1994

D Morikis, and C A Lepre, and P E Wright
Department of Molecular Biology, Scripps Research Institute, La Jolla, CA 92037.

Homonuclear two-dimensional and three-dimensional 1H-NMR spectroscopy has been utilized to study the 15.9-kDa protein soybean leghemoglobin. NMR experiments were performed on the diamagnetic carbon monoxide complex at two temperatures and two pH values. Sequence-specific assignments have been made for 94% of the backbone and approximately 70% of the expected side-chain resonances. The secondary structure of leghemoglobin in solution has been determined on the basis of NOE connectivity patterns, hydrogen exchange and chemical-shift analyses. Leghemoglobin consists of seven helices and, unlike mammalian myoglobins, is missing the D helix. Instead an extended loop, the CE loop, is observed which might have importance for ligand entry into and exit from the protein interior. The hydrogen exchange behavior for the F helix and at the beginning of the A helix suggests different dynamic stability compared to other helical regions in leghemoglobin. Population of a second protein conformation, in which there is perturbation at the A-G-H helix interface, is observed at low pH.

UI MeSH Term Description Entries
D007874 Leghemoglobin A hemoglobin-like oxygen-binding hemeprotein present in the nitrogen-fixing root nodules of leguminous plants. The red pigment has a molecular weight approximately 1/4 that of hemoglobin and has been suggested to act as an oxido-reduction catalyst in symbiotic nitrogen fixation. Leghemoglobin A
D008958 Models, Molecular Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures. Molecular Models,Model, Molecular,Molecular Model
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009682 Magnetic Resonance Spectroscopy Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING). In Vivo NMR Spectroscopy,MR Spectroscopy,Magnetic Resonance,NMR Spectroscopy,NMR Spectroscopy, In Vivo,Nuclear Magnetic Resonance,Spectroscopy, Magnetic Resonance,Spectroscopy, NMR,Spectroscopy, Nuclear Magnetic Resonance,Magnetic Resonance Spectroscopies,Magnetic Resonance, Nuclear,NMR Spectroscopies,Resonance Spectroscopy, Magnetic,Resonance, Magnetic,Resonance, Nuclear Magnetic,Spectroscopies, NMR,Spectroscopy, MR
D010649 Phenylalanine An essential aromatic amino acid that is a precursor of MELANIN; DOPAMINE; noradrenalin (NOREPINEPHRINE), and THYROXINE. Endorphenyl,L-Phenylalanine,Phenylalanine, L-Isomer,L-Isomer Phenylalanine,Phenylalanine, L Isomer
D011487 Protein Conformation The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain). Conformation, Protein,Conformations, Protein,Protein Conformations
D002248 Carbon Monoxide Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed) Monoxide, Carbon
D006859 Hydrogen The first chemical element in the periodic table with atomic symbol H, and atomic number 1. Protium (atomic weight 1) is by far the most common hydrogen isotope. Hydrogen also exists as the stable isotope DEUTERIUM (atomic weight 2) and the radioactive isotope TRITIUM (atomic weight 3). Hydrogen forms into a diatomic molecule at room temperature and appears as a highly flammable colorless and odorless gas. Protium,Hydrogen-1
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D013025 Glycine max An annual legume. The SEEDS of this plant are edible and used to produce a variety of SOY FOODS. Soy Beans,Soybeans,Bean, Soy,Beans, Soy,Soy Bean,Soybean

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