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P K Datta

Publications and source records attributed to P K Datta.

At least 19 recordsLinked to original sources
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↗
PubMed1989

Presence of an intron in elongator methionine-tRNA of Halobacterium volcanii.

The gene for the elongator (internal) methionine transfer RNA (tRNA(mMet)) in the archaebacterium Halobacterium volcanii contains a 75 base pair intron (intervening sequence) and lacks the 3'-terminal CCA sequence of the mature tRNA. There is a single copy of this gene in the genome and it is expressed. Northern hybridization experiments indicate that the precursor is processed to produce mature tRNA and a free intron species. A secondary structure of the transcript can be formed in which the anticodon stem of the tRNA is extended. Two symmetrically placed three-base bulge loops separated by a 4 base pair stem are present in this extension. The cleavage sites for the removal of the intron are placed between the middle and 3' residues of these loops.

Base Sequence↗
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↗
PubMed1986

Identification of the major mannose-binding proteins from chicken egg yolk and chicken serum as immunoglobulins.

Chicken egg yolk contains a mannose-binding protein that could be purified with a modification of the procedure of affinity chromatography and gel filtration used for chicken serum mannose-binding protein. The yolk protein was indistinguishable from the serum protein with respect to apparent molecular masses (169 +/- 7 kDa), subunits (74 kDa and 27 kDa, in approximately 1:1 ratio) produced after denaturation in the presence of mercaptoethanol, immunoreactivity with antibody against the chicken serum mannose-binding protein, amino acid composition, pH optimum for binding, calcium independence of binding, sugar-binding specificity, and specific-binding activity. Moreover, the chicken mannose-binding proteins cross-reacted with gamma-chain-specific antibody against chicken IgG. The binding proteins were identified as IgGs by several other criteria: identical electrophoresis pattern when subjected to reducing and nonreducing NaDodSO4/polyacrylamide gel electrophoresis, cochromatography on a Fractogel TSK HW-55(F) column, similar amino acid composition, and isolation of mannose-binding protein from purified serum IgG at a yield comparable to whole serum. These results support the notion that the mannose-binding proteins from the chicken serum and egg yolk are similar, if not identical, and are a subset of chicken IgG.

Amino Acids↗
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↗
PubMed1983

Cold urticaria.

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Adult↗