Biomedical subjects

G Datta

Publications and source records attributed to G Datta.

26 records · Page 2Linked to original sources

PubMed1992

Reverse micelles of dipalmitoyl phosphatidyl choline in chloroform and their interactions with dapsone.

1H NMR studies of DiPalmitoyl Phosphatidyl Choline (DPPC) in CDCl3 at various concentrations indicate that DPPC exists as reverse micelles for concentrations beyond 6 mM. The chemical environments of the two acyl chains of DPPC are inequivalent and the inequivalence decreases with increasing DPPC concentration. At low concentrations of DPPC (less than 1.0 mM) intramolecular interactions predominate, whereas at high concentrations, intermolecular interactions predominate. Addition of water to this system, at high concentrations of the phospholipid, reduces the intermolecular interactions. In the presence of the antileprotic drug, Diamino Diphenyl Sulfone (DDS or Dapsone), significant shifts were observed only in the choline resonances of DPPC and the amino resonance of the drug, showing that the amino group of DDS interacts with the head group of DPPC.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1989

Mechanism of interaction of the antileukemic drug cytosine arabinoside with aromatic peptides: role of sugar conformation and peptide backbone.

Interaction of the antileukemic drugs, cytosine-arabinoside (Ara-C) and adenosine-arabinoside (Ara-A) and a structural analogue, cytidine, with aromatic dipeptides has been studied by fluorescence and NMR spectroscopy. Ara-C and cytidine bind tryptophanyl and histidyl dipeptides but not tyrosyl dipeptides, while Ara-A does not bind to any of them. Both studies indicate association involving stacking of aromatic moieties. NMR spectra also indicate a protonation of the histidine moiety by Ara-C. In case of cytidine, the chemical shifts observed on binding to His-Phe imply that the backbone protons of the dipeptide participate in the binding. The conformation of the sugar and the base seem to play a very important role in the binding phenomenon as three similar molecules, Ara-C, Ara-A and cytidine bind in totally different ways.

Amino Acid Sequence↗

PubMed1985

Chemical characterization of the dapsone binding site of lysozyme.

The binding of dapsone to hen egg white lysozyme has been studied using fluorescence spectroscopy. At low concentrations the drug binds lysozyme with a Ka = 3.3 X 10(4) M-1 forming a 1:1 complex. At high concentrations the protein was found to bind the drug in a cooperative manner at two sites with an average association constant of 6.3 X 10(4) M-1. Both Trp-108 and Trp-62 of lysozyme are involved in the association process. Acetylation of the lysine residues increased the affinity of the drug to the protein. However, drug association showed no effect on the enzymatic activity of the protein.

Animals↗

PubMed1984

Involvement of tryptophan residues of lysozyme in its binding with cytosine arabinoside.

Cytosine-1-beta-D-arabinofuronaside, an antileukemic drug and hen egg white lysozyme (E.C. 3.2.1.17) form a 1:1 complex with Ka 1.2 X 10(4) M-1 at low drug concentrations. However, association was cooperative in nature at high concentrations with values of Ka = 1.8 X 10(4) M-1 and N = 2. Involvement of tryptophan in the drug protein complex was evident from fluorescence quenching and from the association of the drug with free tryptophan with a Ka = 1.5 X 10(4) M-1. Modification of tryptophan 108 reduced the binding by 89% suggesting a major role for this residue in the binding process. Oxidation of tryptophan 62 and acetylation of lysine residues also decreased the affinity of the drug to the protein by 55 and 66% respectively. Binding improved with increase in temperature and positive values for change in enthalpy and entropy were obtained. Ara-C inhibited lysozyme activity noncompetitively.

Cytarabine↗

PubMed1982