S. S. Sundaresan
University of Madras
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Featured researches published by S. S. Sundaresan.
Acta Crystallographica Section F-structural Biology and Crystallization Communications | 2009
S. S. Sundaresan; P. Ramesh; K. Sivakumar; M. N. Ponnuswamy
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 structure-function 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 image-plate detector system. The crystals of ostrich haemoglobin diffracted to 2.2 A 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 A.
Journal of Synchrotron Radiation | 2013
P. Ramesh; S. S. Sundaresan; Pon. Sathya Moorthy; M. Balasubramanian; M. N. Ponnuswamy
Shortfin mako shark haemoglobin adopts an unliganded deoxy T state conformation, which is shown from the quaternary structural features, interface interactions and heme binding sites of different subunits of haemoglobin with high-resolution X-ray data.
Acta Crystallographica Section E-structure Reports Online | 2009
P. Ramesh; S. S. Sundaresan; Prakasam Thirumurugan; Paramasivan T. Perumal; M. N. Ponnuswamy
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.
Acta Crystallographica Section E-structure Reports Online | 2009
P. Ramesh; S. S. Sundaresan; Neelakandan Vidhya Lakshmi; P. T. Perumal; M. N. Ponnuswamy
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.
Acta Crystallographica Section E-structure Reports Online | 2009
P. Ramesh; S. S. Sundaresan; Neelakandan Vidhya Lakshmi; P. T. Perumal; M. N. Ponnuswamy
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.
Protein and Peptide Letters | 2008
M. N. Ponnuswamy; S. S. Sundaresan; Packianathan Charles; K. Neelagandan
Hemoglobin (Hb) is a tetrameric protein, which contains four heme prosthetic groups, and each one is associated with a polypeptide chain. Herein, we report the rabbit hemoglobin which has intrinsically high oxygen affinity and possess highest sequence identity with human hemoglobin. The purified hemoglobin has been tried to crystallize in different crystallization conditions owing to its formation of various crystal systems. The rabbit Hb crystals were grown using PEG 3,350 as the precipitant at 18 degrees C. The crystals of rabbit Hb belongs to triclinic space group P1 with one molecule (alpha2beta2) in the asymmetric unit.
Acta Crystallographica Section E-structure Reports Online | 2008
S. S. Sundaresan; P. Ramesh; Natarajan Arumugam; R. Raghunathan; M. N. Ponnuswamy
In the title molecule, C35H33N3O6, the pyrrolidine ring adopts a twist conformation. The molecules are paired into centrosymmetric dimers by weak intermolecular C—H⋯O hydrogen bonds. The dimers interact further again via C—H⋯O hydrogen bonds and N—H⋯O intramolecular interaction also stabilize the crystal packing.
Acta Crystallographica Section E-structure Reports Online | 2008
S. S. Sundaresan; P. Ramesh; Natarajan Arumugam; R. Raghunathan; M. N. Ponnuswamy
In the title compound, C37H34ClN3O6, the pyrrolidine and piperidine rings adopt envelope and boat conformations, respectively. The β-lactam ring is planar and forms dihedral angles of 21.3 (2) and 73.9 (2)°, respectively, with the attached methoxyphenyl and phenyl rings. Intramolecular C—H⋯O and C—H⋯N hydrogen bonds are observed. Centrosymmetrically related molecules are linked together by weak C—H⋯O hydrogen bonds to form dimers.
Acta Crystallographica Section E-structure Reports Online | 2010
S. S. Sundaresan; P. Ramesh; Natarajan Arumugam; Raghavachary Raghunathan; M. N. Ponnuswamy
In the title molecule, C37H35N3O6, the pyrrolidine ring adopts a twist conformation and the piperidine ring is in a distorted boat conformation. One of the phenyl rings is disordered over two positions with occupancies of 0.54 (2) and 0.46 (2) and the ethyl carboxylate group is also disordered over two orientations with occupancies of 0.75 (1) and 0.25 (1).
Acta Crystallographica Section E-structure Reports Online | 2009
P. Ramesh; S. S. Sundaresan; Prakasam Thirumurugan; Paramasivan T. Perumal; M. N. Ponnuswamy
There are two independent molecules in the asymmetric unit of the title compound, C18H12ClN3O. The two pyridine rings are almost coplanar [dihedral angles between the rings: 2.87 (15) and 5.36 (16)°] while the chlorophenyl rings are twisted out of the plane of the adjacent bipyridine ring by 44.1 (1) and 43.8 (1)° in the two molecules. The crystal packing is stabilized by C—H⋯N and C—H⋯Cl interactions.