PubMed Health⌕ Search

Biomedical subjects

T K Datta

Publications and source records attributed to T K Datta.

At least 19 recordsLinked to original sources
PubMed1996

Possible mechanism for the inhibition of lectin-erythrocyte interaction in presence of endogenous lectin receptor.

The presence of hydrophobic sites in the lectin-I molecule was indicated by hydrophobic probes like 1-anilinonapthalene-8-sulfonic acid (ANS), 2-p-toluidinyl napthalene-6-sulfonic acid (TNS). N-phenyl-1-napthylamine (NA) and rose bengal (RB). This was further confirmed by amino acid modifications in the hydrophobic region of the lectin-I molecule. The binding of ANS, TNS, NA and RB to lectin-I was affected in the presence of NaCl. The involvement of hydrophobic interactions in rice-bean lectin-I-endogenous lectin receptor (ELR) complex were indicated by alterations in the circular dichroism and fluorescence emission spectra. The percentage of beta-conformation (55-63%) of lectin-I was decreased by addition of ELR. ELR on reacting with lectin-I reduced the fluorescence emissions of the hydrophobic probes while fluorescence emission of ANS, TNS, NA and RB were greatly enhanced in presence of lectin-I alone. N-aceyl-galactosamine did not change the fluorescence emissions of any of the hydrophobic probes in presence or in absence of lectin-I. This demonstrates that carbohydrate and hydrophobic sites may be different and non-interacting. It is proposed that the ELR in reacting with lectin-I, induced conformational changes in the lectin-I molecule and thereby affected its erythroagglutinating activity with human blood group "A" erythrocytes.

1-Naphthylamine↗
PubMed1996

Serine proteinase from rice bean.

A trypsin like serine-proteinase of M(r) 16,000 Da, optimally active at pH 8.4 on N-benzoyl-arginine ethyl ester (BAEE) was purified from 4-day old germinated seeds of rice bean, Vigna umbellata (Thunb), by ammonium sulphate precipitation, gel filtration, ion-exchange chromatography and by high performance liquid chromatography (HPLC). The purity of the enzyme was checked by polyacrylamide gel electrophoresis (PAGE). The enzyme activity was studied on natural substrates like casein, haemoglobin and vicilin, a rice bean storage protein. The activity of the enzyme was completely inhibited by phenylmethylsulfonyl fluoride, but not by iodoacetamide and HgCl2, suggesting it to be a serine protease. Loss of activity in presence of EDTA was reversed by addition of Ca2+.

Calcium↗
PubMed1991

Characterization of a naturally occurring protease inhibitor in the hemolymph of the scorpion, Heterometrus bengalensis.

A protease inhibitor has been purified by ultracentrifugation, affinity chromatography on trypsin-sepharose 4B, and chromatofocusing on PBE-94 from hemolymph of the scorpion Heterometrus bengalensis. Homogeneity of the protease inhibitor was demonstrated by high performance liquid chromatography (HPLC). The protease inhibitor is a monomeric glycoprotein with a molecular weight of 120,000 dalton, which is stable between pH 4 and pH 8. The molecule inhibits serine proteases like trypsin and alpha-chymotrypsin and shows a noncompetitive mode of inhibition towards trypsin, with a Ki value of 6.1 x 10(-6) mM. Amino acid analysis shows a preponderance of aspartic acid, glutamic acid, serine, and glycine. The protease inhibitor is efficient in inhibiting phenoloxidase activity in both the hemolymph and the isolated phenoloxidase. Melanin synthesis by phenoloxidase may be influenced by this protease inhibitor.

Amino Acids↗
PubMed1989

Purification of a unique glycoprotein that enhances phenol oxidase activity in scorpion (Heterometrus bengalensis) haemolymph.

A monomeric glycoprotein (SGP) of Mr 32,000 was isolated to purity from scorpion (Heterometrus bengalensis) haemolymph by (NH4)2SO4 fractionation, chromatofocusing and h.p.l.c. The homogeneity of SGP is confirmed by polyacrylamide-gel electrophoresis. SGP is soluble in 100%-satd. (NH4)2SO4 solution. Needle-shaped crystals of SGP were obtained in an aqueous environment. The glycan part of the molecule contains arabinose, which does not commonly occur in animal glycoproteins. Amino acid analysis demonstrated a preponderance of glycine, tyrosine and glutamic acid. SGP enhances phenol oxidase (EC 1.14.18.1) activity.

Animals↗
PubMed1988

Enhancement of lectin-erythrocyte agglutination by gums.

The erythroagglutinating activity of purified Vicia faba lectin was enhanced in the presence of gums; gum guar caused the highest enhancement. Circular dichroism probe demonstrated 40-57% beta-conformation and 4-23% alpha-conformation of the lectin at pH 7.2 depending upon the analytical methods used. The beta-conformations of untreated and modified V. faba lectins were increased in the presence of gums. The mixing of gum guar with lectin and with modified lectin, respectively, led to the highest values of beta-conformational change in the protein molecule, thereby increasing the number of receptor sites of the lectin molecule. The enhancement of the activity of V. faba lectin in the presence of gum guar might be due to the conformational change of the protein molecule.

Animals↗
PubMed1988

Purification of human erythrocytes specific lectins from rice bean, Phaseolus calcaratus syn. Vigna umbellata, by high-performance liquid chromatography.

Two lectins, an N-acetylgalactosamine-binding lectin, lectin-I, which reacts specifically with human erythrocytes of blood group A, and a galactose-binding lectin, lectin-II, which is specific for human blood group B erythrocytes, have been isolated and purified from rice bean, Phaseolus calcaratus syn. Vigna umbellata, by a salt solubility pH-dependent method, chromatofocusing and high-performance liquid chromatography. The homogeneity of the lectins was determined by liquid chromatography and polyacrylamide gel electrophoresis. The purified lectin-I of molecular mass 80,000 is possibly composed of two subunits of molecular mass ca. 18,000 and 22,000, respectively, whereas lectin-II of molecular mass 100,000 appears to be composed of a monomeric protein of molecular mass 25,000. One endogenous lectin-binding protein was also isolated and purified by liquid chromatography. The endogenous lectin-binding protein of molecular mass 40,000 affects the activity of the A-group specific lectin more than that of the B-group specific lectin. The endogenous lectin-binding protein appears to be composed of a monomeric protein of molecular mass 20,000.

Blood Proteins↗
PubMed1988

Circular dichroism and fluorescence investigations on Vicia faba lectin-saccharide binding.

Vicia faba lectin contained 40-57% beta-conformation, 4-23% alpha-conformation along with random coil at pH 7.2 depending upon the analytical methods used. The percentage of beta-conformation increased with the addition of N-acetyl-D-glucosamine or methyl alpha-D-mannopyranoside. The structural transitions of V. faba lectin were affected by alkali at pH 9.6 and 10.6. Binding constants and free energy changes for the interaction between V. faba lectin and N-acetyl-D-glucosamine and methyl alpha-D-mannopyranoside were estimated at pH 7.2 using the c.d. and fluorescence methods.

Acetylglucosamine↗
PubMed1988

Acetylcholinesterase (EC 3.1.1.7), a neurotransmitter enzyme in scorpion hemolymph.

Acetylcholinesterase (AchE: EC 3.1.1.7) was identified and purified from the hemolymph of the scorpion Heterometrus bengalensis. The purity of the enzyme was determined by polyacrylamide gel electrophoresis (PAGE). The molecular weight of the enzyme, determined by sodium dodecyl sulfate-PAGE, was 80,000. The purified AchE hydrolysed acetylthiocholine iodide, but it did not react with butyrylthiocholine iodide. BW284C51, a specific inhibitor of AchE, strongly inhibited the enzyme. The known inhibitor (tetramonoisopropylpyrophosphortetramide) of pseudocholinesterase did not produce any inhibition of the enzyme activity. The purified AchE of scorpion hemolymph was vulnerable to high substrate concentration. The presence of Cu2+ and Ni2+ reduced the enzyme activity, whereas the metal ion, Sn2+, enhanced AchE activity. Ca2+ produced neither inhibition nor activation. (Na+, K+)-ATPase and Mg2+-ATPase activities were greatly enhanced by the purified AchE.

Acetylcholinesterase↗
PubMed1984

Purification and partial characterization of an erythroagglutinin from the hemolymph of scorpion, Heterometrus bengalensis.

An erythroagglutinin from the hemolymph of the scorpion, Heterometrus bengalensis, has been purified by gel filtration and ion-exchange chromatography. Its homogeneity has been demonstrated by polyacrylamide gel electrophoresis. The purified agglutinin appears to be a monomeric protein having a possible molecular weight between 146,000 and 148,000. It has no divalent cation requirement for erythroagglutination. The erythroagglutination is not inhibited by saccharides, glycoproteins and mucin. Identical erythroagglutination pattern is obtained with normal as well as neuraminidase treated erythrocytes.

Animals↗
PubMed1984

Isolation and characterization of Vicia faba lectin affinity purified on chitin column.

A lectin from early long pod var. of Vicia faba seed has been purified to homogeneity on chitin. The purified lectin is shown to be homogeneous in nature by Bio Gel P - 150 gel filtration, fast protein liquid chromatography and polyacrylamide gel electrophoresis. The lectin is a glycoprotein with molecular weight of 51,000. The lectin molecule is possibly composed of two types of subunits devoid of any covalent linking through sulfhydryl groups, with molecular weights 9,000 and 15,000 respectively in the ratio 2:2. The purified lectin shows a high affinity for N-acetyl-D-glucosamine (GlcNAc). Amino acid analyses show that cysteine and methionine are absent, and a high proportion of aspartic acid and glutamic acid are present in the protein molecule. The extinction coefficient of the purified lectin is 7.22. The lectin behaves as a 'cold agglutinin' displaying stronger agglutination than the naturally occurring ABO agglutinin in the cold.

Amino Acids↗
PubMed1981

Identification, isolation and some properties of lectin from the seeds of Indian coral tree [Erythrina variegata (Linn.) var. orientalis (Linn.) Merrill].

A D-galactose-binding lectin agglutinating human erythrocytes has been purified from the seeds of the Indian coral tree (Erythrina variegata (Linn.) var. orientalis (Linn.) Merrill] by affinity chromatography on acid-treated Sepharose-6B gel. It has a higher reactivity for O-group erythrocytes. The lectin is a glycoprotein having a leucoagglutinating property.

Carrier Proteins↗