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Biomedical subjects

K B Roy

Publications and source records attributed to K B Roy.

26 records · Page 2Linked to original sources
PubMed1986

Molecular conformation of gonadoliberin using two-dimensional NMR spectroscopy.

Complete resonance assignments of the proton NMR spectrum of gonadoliberin (in its native amide and free acid forms) have been obtained using two-dimensional nuclear magnetic resonance spectroscopy under three different environmental conditions, namely, dimethyl sulphoxide solution, aqueous solution and lipid-bound form in model membranes. The proton chemical shifts in the three cases have been compared to derive information about inherent conformational characteristics of the molecule. It has been inferred that the molecule possesses no short-range or long-range order under any of the three solvent conditions. However, there is a nonspecific increase in the linewidths when gonadoliberin is bound to model membranes, indicating a reduced internal motion in the molecule due to lipid-peptide interactions.

Deuterium↗
PubMed1985

Resonance assignment of the 500-MHz proton NMR spectrum of self-complementary dodecanucleotide d-GGATCCGGATCC: altered conformations at BamHI cleavage sites.

Resonance assignments of nonexchangeable base and sugar protons of the self-complementary dodecanucleotide d-GGATCCGGATCC have been obtained by two-dimensional NMR methods and strategies derived from interproton distance calculations on different secondary structures of nucleic acids. Conformational details about the glycosidic dihedral angle and sugar pucker have been derived from the relative intensities of cross peaks in the two-dimensional J-correlated and nuclear Overhauser enhancement correlated spectra in D2O solution. It is observed that d-GGATCCGGATCC assumes a predominantly B-type conformation with sequence-dependent changes along the chain. The recognition site of BamHI shows a distinctly different geometrical environment. The sugar rings of G1 and G7 assume a C3'-endo geometry while the rest of the sugars possess C2'-endo geometry.

Base Sequence↗
PubMed1983

A thermally driven interconversion of B and Z-dna.

CD and IR studies show that poly(dG-dMeC) in dilute Mg++ and Na+ solutions (e.g., 2 mM Mg++ and 55 mM Na+) undergoes reversible thermal interconversion of B and Z forms, in contrast to previous reports that the transition is independent of temperature and has an enthalpy change of zero. The B conformation is stable under the above conditions at lower temperature (approximately 5 degrees) and the Z form above approximately 20 degrees. The conversion is relatively slow in both directions, but is more rapid in the Z leads to B direction.

Circular Dichroism↗
PubMed1982

Binding isotherms of nucleosides and polynucleotides measured by continuous ultrafiltration at constant volume: a rapid and precise technique.

Equilibrium binding isotherms have been measured as a function of temperature for the interaction of 2- and 8-aminoadenosine with poly(U) by continuous, constant-volume ultrafiltration. An analytical method is described for determining the entire isotherm in a single experiment on a preequilibrated ligand--polymer solution. The method is shown to produce the same results as classical equilibrium dialysis but to be much more rapid and convenient. Values of the enthalpy, equilibrium constant, and free energy of stacking as a function of temperature are derived from the binding data. Stoichiometry of interaction is obtained from the diafiltration profiles as well as from the binding isotherms. Over the temperature range studied, the cooperativity of binding is observed to increase with rising temperature.

Adenosine↗
PubMedDate not supplied

Testing of newly developed glycophospholipid antigen for the detection of P. falciparum malaria by laser light immunoassay in endemic and non-endemic areas.

A glycophospholipid (GPL) antigen isolated from Plasmodium falciparum culture supernatant has been tested for its antigenicity. Detection of malaria positive known blood samples and unknown field samples from endemic and non-endemic areas were compared. In this study laser light scattering immunoassay (LIA) was used for the detection of P. falciparum malaria. Test results of control (malaria negative samples from Surat) were compared with known positive samples and unknown malaria positive field samples. A positive correlation has been observed (97%) in falciparum positive samples from laboratory and unknown samples from endemic area (Haldwani) by LIA method using GPL antigen. From the results of the study it was found that GPL antigen has a better antigenic property and can detect almost all the cases of Pf malaria by LIA method.

Adult↗