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Biomedical subjects

K Ravikumar

Publications and source records attributed to K Ravikumar.

23 records · Page 2Linked to original sources
PubMed1994

Non-steroidal anti-inflammatory drugs. III. Structure of indoprofen: 2-[4-(1-oxo-2-isoindolinyl)phenyl]propionic acid.

Indoprofen, 4-(1,3-dihydro-1-oxo-2H-isoindol-2-yl)-alpha-methylbenzeneaceti c acid, C17H15NO3, a non-steroidal anti-inflammatory agent, falls into the class of phenylpropionic acids that includes ibuprofen, ketoprofen and flubirprofen. It adopts a planar conformation apart from the carboxylic acid group. There is a small twist of 8.8 (2) degrees between the mean planes of the isoindolinyl and phenyl rings. The rotation of the carboxyl group out of the plane of the adjacent phenyl ring seems to be connected with anti-inflammatory activity and is similar to that found in other 2-phenylpropionic acids. A pair of intermolecular hydrogen bonds connects two carboxylic acid groups across a centre of symmetry with an O...O distance of 2.61 (1) A.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1990

The use of single-wavelength anomalous scattering to solve the crystal structure of a gramicidin A/caesium chloride complex.

Single-wavelength Cu K alpha anomalous scattering has been used to determine the structure of a crystalline complex of gramicidin A and caesium chloride. The asymmetric unit in these crystals, with space group P2(1)2(1)2(1) and a = 32.118 (6), b = 52.103 (12), c = 31.174 (7) A, contains four independent monomers (two dimers) of the pentadecapeptide. This structure falls in an intermediate size range for which direct methods and multiple isomorphous replacement are generally not successful for obtaining phase information. However, using the Bijvoet differences and the partial structure of the caesium atoms which have been incorporated in the crystals, it has been possible to obtain information on this crystal form. Because the caesium atoms dominate the scattering of these crystals, inclusion of the Friedel mate information in the restrained least-squares refinement has been essential. These studies extend the utility of single-wavelength anomalous-scattering phase determination to a macromolecular structure in which the partial structure of the anomalous scatterer is large.

Cesium↗
PubMed1989

Littre's hernia in a child--an operative surprise (a case report).

The incidence of Littre's hernia in children is unknown. The diagnosis is usually made at operation or autopsy. One case in an eight month old infant is described. Heterotropic mucoglandular tissue causing nodularity and adhesions was noted in the diverticulum. Though histological findings in Littre's hernia are not mentioned in previous reports, we believe that Littre's hernia could often be associated heterotropic mucosa.

Hernia, Inguinal↗
PubMed1988

The gramicidin pore: crystal structure of a cesium complex.

Gramicidin, a linear polypeptide composed of hydrophobic amino acids with alternating L- and D- configurations, forms transmembrane ion channels. The crystal structure of a gramicidin-cesium complex has been determined at 2.0 angstrom resolution. In this structure, gramicidin forms a 26 angstrom long tube comprised of two polypeptide chains arranged as antiparallel beta strands that are wrapped into a left-handed helical coil with 6.4 residues per turn. The polypeptide backbone forms the interior of the hydrophilic, solvent-filled pore and the side chains form a hydrophobic and relatively regular surface on the outside of the pore. This example of a crystal structure of a solvent-filled ion pore provides a basis for understanding the physical nature of ion translocation.

Binding Sites↗