• M Jamaluddin

      Articles written in Journal of Biosciences

    • A rapid and gentle method for the salt extraction of chromatin core histones H2A, H2B, H3 and H4 from rat liver nuclei

      M Jamaluddin Mohananphilip H Sharat Chandra

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      A complex of histones H2A, H2B, H3 and H4 has been isolated from purified rat liver nuclei by a method which is both gentle and rapid. Nuclei were homogenised in 0.25 M sucrose and the residual nuclear material obtained after centrifligation was adsorbed on calcium phosphate gel. After removing histone H1 from the adsorbed material by washing with 1M NaCl in 25 mM sodium phosphate buffer, pH 6.0, histones H2A, H2B, H3 and H4 were eluted together, with 2 M NaCl in 25 mM sodium phosphate buffer, pH 7.0. The core histones so obtained migrated as a single sharp band on polyacrylamide gel electrophoresis under non-denaturing conditions. Fractionation of the freshly prepared core histones on a Sephadex G-100 column yielded two major protein peaks. The peak having the larger elution volume contained histones H2A and H2B in equal amounts while the peak with the smaller elution volume contained all the four histones. Histones H3 and H4 were present in larger proportions in the second peak.

    • N-[2-Naphthyl]-glycine hydrazide, a potent inhibitor of DNA-dependent RNA polymerase ofMycobacterium tuberculosis H37RV

      Rekha Prabhu G Ramananda Rao M Jamaluddin T Ramakri Shnan

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      N-[2-Naphthyl]-glycine hydrazide has been shown for the first time as a potent inhibitor of the DNA-dependent RNA polymerase (EC ofMycobacterium tuberculosis H37Rv. At a concentration of 10-9 M, the compound shows maximum inhibition of the enzyme, the inhibition being less at higher concentrations. It is suggested that the novel type of inhibition pattern may be due to hydrophobic interactions occurring between the molecules of the compound at higher concentrations. The finding that there is a shift in the λmax of the compound could also account for this phenomenon. The effect of this compound was also tested on DNA-dependent RNA polymerases from an eukaryotic fungus,Microsporum canis. At a concentration of 10−9 M it inhibits RNA polymerase II (32%) but not RNA polymerasesI andIII

    • Adenosine and ATP: mutually exclusive modifiers of the kinetics of ADP-induced aggregation of calf-platelets

      M Jamaluddin L K Krishnan

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      Modulations of initial rate kinetics of ADP-induced aggregation of citrated calf platelet-rich plasma by adenosine and ATP were investigated employing a spectrophotometric platelet aggregation assay. The data were analysed according to the tenets of sequential shape-change and interaction model of aggregation. Adenosine and ATP increased the slopes and intercepts of double-reciprocal plots of ADP-aggregation kinetics. Examination of their slope and intercept effects together with their effects individually and in combination, on aggregation rates, suggested that adenosine and ATP acted at multiple, nonoverlapping, sites.

    • Platelet activating factor-induced aggregation of calf platelets: Apparent positive cooperativity in the kinetics and non competitive inhibition by diltiazem

      M Jamaluddin A Thomas

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      Aggregation of calf platelets by platelet activating factor was characterized by a spectrophotometric method. The aggregation kinetics of both platelet-rich plasma and purified platelets showed concave up double-reciprocal plots and linear Hill plots withh > 1 (1.7 ± 02) consistent with positive cooperativity. Comparable values of maximum rates of aggregation(R) were obtained with platelet-rich plasma (0.25 ± 0.08) and purified platelets (0.28 ± 0.18) but the half-maximal saturation concentration (S0.5) differed greatly between platelet-rich plasma (6 ± 3 nM) and purified platelets (0.28 ± 0.18 nM). An Arrhenius activation energy of 21 ±2 kcal/mol was found for aggregation of purified platelets. Diltiazem was inhibitory with half-maximal inhibitory concentration (I0.5) of 4 M but the inhibition was not competitive. Diltiazem inhibited rates but not the extent of shape-change. The receptor-antagonist and sulphydryl reagent N-ethylmaleimide and the platelet antagonistic omega-3-fatty acid, 5,8,11,14,17-eicosa pentaenoic acid, inhibited both rates and extent of shape-change reactions and inhibited aggregation competitively (I0.5 ∼ 5 M). Eicosa pentaenoic acid at > 25 M could abolish shape-change reactions and at 50 M served as an activator of platelets and the activation was enhanced by aspirin (1 mM). Although N-ethylmaleimide at > 20 M could also induce platelet activation it failed to induce aggregation and aspirin had no effect on the shape-change reactions induced by it.

  • Journal of Biosciences | News

      Forthcoming Special issue.

    • To trigger further research on plant mitochondria, the Journal of Biosciences is bringing out a special issue titled "Plant Mitochondria: Properties and Interactions with Other Organelles".

      Plant mitochondria are quite distinct and have unique features, such as a cyanide-insensitive alternate pathway. They also interact with chloroplasts to optimize photosynthetic carbon assimilation.

      Submissions are welcome until 30 July 2023. The contributions can be original articles, short communications, reviews, or mini-reviews on any topic related to plant mitochondria.

      Authors can submit their articles online at https://www.editorialmanager.com/jbsc/default2.aspx

      Posted on April 12, 2023
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      Posted on July 25, 2019

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