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. Mostly the pisces species are cold blooded in nature. Distinctly, the SMSs are warmblooded animals with an advanced circulatory system. SMSs are capable of maintaining elevated muscle temperatures up to 33 K above the ambient water temperatures at a depth of 150-500 m. SMSs have a diverged air-breathing mechanism compared with other vertebrates. The haemoglobin molecule consists of four polypeptide chains, namely two chains, each with 140 amino acids and two chains each having 136 amino acids. The SMS Hb was found to crystallize in monoclinic space group P2 1 using the hanging-drop vapourdiffusion method at room temperature. The crystal packing parameters for the SMS Hb structure contain one whole biological molecule in the asymmetric unit with a solvent content of 47%. The SMS Hb quaternary structural features interface-interface interactions and heme binding sites are discussed with different state Hbs and the results reveal that SMS Hb adopts an unliganded deoxy T state conformation.

Haemoglobin is a tetrameric protein that carries oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs. The oxygen-binding properties of haemoglobin are regulated through the binding of allosteric effectors. The respiratory system of avian species is unique and complex in nature when compared with that of mammals. In avian species, inositol pentaphosphate (inositol-P 5 ) is present in the erythrocytes of the adult and is thought to be the major factor responsible for the relatively high oxygen affinity of the whole blood. The ostrich (Struthio camelus) is a large flightless bird which contains inositol tetrakisphosphate (inositol-P 4 ) in its erythrocytes and its whole blood oxygen affinity is higher. Efforts have been made to explore the structurefunction relationship of ostrich haemoglobin. Ostrich haemoglobin was purified using ion-exchange chromatography. Haemoglobin crystals were grown by the hanging-drop vapour-diffusion method using PEG 3350 as the precipitant in 50 mM phosphate buffer pH 7.2. Data were collected using a MAR345 imageplate detector system. The crystals of ostrich haemoglobin diffracted to 2.2 Å resolution. They belonged to the orthorhombic space group P2 1 2 1 2 1 with one whole biological molecule in the asymmetric unit; the unit-cell parameters were a = 80.93, b = 81.68, c = 102.05 Å .

In the title compound, C21H15N5O2, the pyrrolidine ring adopts a twist conformation. Both the oxindole rings are planar [maximum deviations of 0.076 (1) and 0.029 (1) Å in the two rings] and are oriented at a dihedral angle of 72.7 (1)°. The crystal structure is stabilized by C—H⋯O, N—H⋯O, N—H⋯N and C—H⋯π inter­actions.

In the title compound, C23H18N2O4·H2O, the two oxindole rings subtend a dihedral angle of 54.29 (5)°. The crystal structure is stabilized by intermolecular N—H⋯O, O—H⋯O and C—H⋯π inter­actions.

The title compound, C25H14Cl2N4, crystallizes with two independent mol­ecules in the asymmetric unit. The two pyridine rings are almost coplanar, making dihedral angles of 3.2 (1) and 8.6 (1)° in the two independent mol­ecules. The dichloro­phenyl and indole rings are twisted away from the bipyridine ring by 64.32 (5) and 18.46 (4)°, respectively in the first molecule and by 51.0 (1) and 27.99 (5)°, respectively in the second molecule. The crystal packing is stabilized by C—H⋯N, C—H⋯Cl, N—H⋯N and C—H⋯π inter­actions.