Molecular Insights of an Avian Species with Low Oxygen Affinity, the Crystal Structure of Duck T-State Methemoglobin.

Hemoglobin (Hb) is the key metalloprotein within red blood cells involved in oxygen transportation from lungs to body cells. The heme-iron atom inherent within Hb effectuates the mechanism of oxygen transportation and carbon dioxide removal. Structural investigations on avian Hb are limited when compared with the enormous work has been carried out on mammalian Hb.

Structural studies of hemoglobin from two flightless birds, ostrich and turkey: insights into their differing oxygen-binding properties.

Crystal structures of hemoglobin (Hb) from two flightless birds, ostrich (Struthio camelus) and turkey (Meleagris gallopova), were determined. The ostrich Hb structure was solved to a resolution of 2.22 Å, whereas two forms of turkey Hb were solved to resolutions of 1.

Crystal structure of hemoglobin from mouse (Mus musculus) compared with those from other small animals and humans.

Mice (Mus musculus) are nocturnal small animals belonging to the rodent family that live in burrows, an environment in which significantly high CO levels prevail. It is expected that mouse hemoglobin (Hb) plays an important role in their adaptation to living in such a high-CO environment, while many other species cannot. In the present study, mouse Hb was purified and crystallized at a physiological pH of 7 in the orthorhombic space group P222; the crystals diffracted to 2.

Semi-quantitative assessment of diffuse hepatic uptake seen in I-131 scans - an indicator of functioning thyroid tissue and disease burden in differentiated thyroid cancer.

Background: To semi-quantitatively analyze liver uptake of I-131 in diagnostic and post-therapy scans by calculating hepatic to thigh ratios (HTR) and evaluate its clinical significance in management of differentiated thyroid cancer.

Method: Two hundred forty-nine patients were included in the study. Hepatic to thigh ratio (HTR) of counts were calculated for 249 diagnostic and 104 post-therapy scans.

Synthesis, spectroscopic, dielectric, molecular docking and DFT studies of (3E)-3-(4-methylbenzylidene)-3,4-dihydro-2-chromen-2-one: an anticancer agent.

Background: Coumarin (2-chromen-2-one) and its derivatives have a wide range of biological and pharmaceutical activities. They possess antitumor, anti-HIV, anticoagulant, antimicrobial, antioxidant, and anti-inflammatory activities. Synthesis and isolation of coumarins from different species have attracted the attention of medicinal chemists.

Crystal structure analysis of a hypothetical protein (MJ0366) from Methanocaldococcus jannaschii revealed a novel topological arrangement of the knot fold.

The crystal structure of a hypothetical protein MJ0366, derived from Methanocaldococcus jannaschii was solved at 1.9 Å resolution using synchrotron radiation. MJ0366 was crystallized as a monomer and has knot structural arrangement.

Crystal structure of piperazine-1,4-diium bis-(4-amino-benzene-sulfonate).

The asymmetric unit of the title salt, C4H12N2 (2+)·2C6H6NO3S(-), consists of half a piperazindiium dication, located about an inversion centre, and a 4-amino-benzene-sulfonate anion. The piperazine ring adopts a chair conformation. In the crystal, the cations and anions are linked via N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional framework.

Revelation of endogenously bound Fe(2+) ions in the crystal structure of ferritin from Escherichia coli.

Ferritin is an iron regulatory protein. It is responsible for storage and detoxification of excess iron thereby it regulates iron level in the body. Here we report the crystal structure of ferritin with two endogenously expressed Fe atoms binding in both the sites.

The crystal structure of oxy hemoglobin from high oxygen affinity bird emu (Dromaius novaehollandiae).

Hemoglobin is an honorary enzyme, a two-way respiratory carrier, transporting oxygen from the lungs to the tissues and facilitating the return transport of carbon dioxide. Hemoglobin has high affinity for oxygen and low affinity for carbon dioxide and other substances in the arterial circulation, whereas in the venous circulation these relative affinities are upturned. The oxygen affinity of hemoglobin increases with the fall in temperature and decreases with the increase in pH and 2, 3-bisphosphoglycerate; point mutations also affect the tetrameric arrangement and alter the oxygen affinity.

Structure of liganded T-state haemoglobin from cat (Felis silvestris catus), a low oxygen-affinity species, in two different crystal forms.

Haemoglobin (Hb) is an iron-containing metalloprotein which plays a major role in the transportation of oxygen from the lungs to tissues and of carbon dioxide back to the lungs. Hb is in equilibrium between low-affinity tense (T) and high-affinity relaxed (R) states associated with its unliganded and liganded forms, respectively. Mammalian species can be classified into two groups on the basis of whether they express `high' or `low' oxygen-affinity Hbs.

Crystal structure of the single-stranded RNA binding protein HutP from Geobacillus thermodenitrificans.

RNA binding proteins control gene expression by the attenuation/antitermination mechanism. HutP is an RNA binding antitermination protein. It regulates the expression of hut operon when it binds with RNA by modulating the secondary structure of single-stranded hut mRNA.

3-Isopropyl-1-{2-[(1-methyl-1H-tetra-zol-5-yl)sulfan-yl]acet-yl}-2,6-di-phenyl-piperidin-4-one hemihydrate.

In the title compound, C24H27N5O2S·0.5H2O, the piperidine ring adopts a distorted boat conformation. The phenyl rings subtend dihedral angles of 69.

3-Ethyl-cis-2,6-di-phenyl-piperidine.

In the title compound, C19H23N, the piperidine ring adopts a chair conformation. The phenyl rings at the 2,6-positions of the piperidine ring occupy equatorial orientations. The crystal structure features C-H⋯π inter-actions.

r-2,c-6-Di-phenyl-piperidine.

In the title compound, C17H19N, the piperidine ring adopts a chair conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring subtend dihedral angles of 81.04 (7) and 81.

Structural studies of haemoglobin from pisces species shortfin mako shark (Isurus oxyrinchus) at 1.9 Å resolution.

Haemoglobin (Hb) is a tetrameric iron-containing protein that carries oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs. Pisces are the advanced aquatic vertebrates capable of surviving at wide depth ranges. The shortfin mako shark (SMS) is the pelagic, largest, fastest and most sophisticated species of the shark kingdom with well developed eyes.

1-Di-chloro-acetyl-t-3-isopropyl-r-2,c-6-di-phenyl-piperidin-4-one.

In the title compound, C22H23Cl2NO2, the piperidine ring adopts a twist-boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring subtend dihedral angles of 60.6 (2) and 84.

Ethyl 3-(4-chloro-phen-yl)-2-phenyl-3-(4-phenyl-1,2,3-selena-diazol-5-yl)propano-ate.

In the title compound, C25H21ClN2O2Se, the selena-diazole ring is almost planar [maximum deviation = 0.004 (2) Å], and the adjacent benzene ring is twisted by 50.6 (1)° with respect to this ring.

4-(2-Hy-droxy-phen-yl)-3,5-di-thia-hepta-ne-dioic acid.

In the crystal of the title compound, C11H12O5S2, mol-ecules are linked by O-H⋯O hydrogen bonds and C-H⋯O inter-actions, forming a three-dimensional network.

2-Chloro-1-(2,4,4-trimethyl-2,3,4,5-tetra-hydro-1H-1,5-benzodiazepin-1-yl)ethanone.

In the title compound, C14H19ClN2O, the diazepine ring adopts a boat conformation. The Cl atom of the chloro-acetyl group is trans to the N atom of the diazepine ring. In the crystal, the mol-ecules form chains running along the diagonal of the ac plane through N-H⋯O hydrogen bonds.

3,5-Dimethyl-1-{2-[(5-methyl-1,3,4-thia-diazol-2-yl)sulfan-yl]acet-yl}-2,6-diphenylpiperidin-4-one.

In the title compound, C24H25N3O2S2, the piperidine ring adopts a distorted boat conformation. The phenyl rings subtend angles of 75.6 (1)° and 86.

1-(2,2-Di-chloro-acet-yl)-3-ethyl-2,6-di-phenyl-piperidin-4-one.

The asymmetric unit of the title compound, C21H21Cl2NO2, contains two independent mol-ecules that show similar geometrical features. The piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring are oriented at angles of 65.

2-Amino-6-methyl-pyridinium 4-hy-droxy-benzoate.

In the title mol-ecular salt, C6H9N2 (+)·C7H5O3 (-), the dihedral angle between the benzene ring and the CO2 group in the anion is 6.1 (2)°. In the crystal, the cation and anion are linked by N-H⋯O and C-H⋯O hydrogen bonds, and the anions are connected by O-H⋯O hydrogen bonds, forming a three-dimensional network.

1-Dichloro-acetyl-t-3,t-5-dimethyl-r-2,c-6-diphenyl-piperidin-4-one.

In the title compound, C21H21Cl2NO2, the piperidine ring adopts a distorted boat conformation. The phenyl rings substituted at the 2- and 6-positions of the piperidine ring subtend angles of 87.9 (7) and 70.