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    • Studies on glutamine synthetase. Purification of the enzyme from mung bean (Phaseolus aureus) seedlings and modulation of the enzyme-antibody reaction by the substrates

      S Seethalakshmi N Appaji Rao

      Volume 1 Issue 1 March 1979 pp 13-24

    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jbsc/001/01/0013-0024

    • Keywords

       

      Mung bean; glutamine synthetase; antibody interactions; Phaseolus aureus

    • Abstract

       

      Glutamine synthetase (L-glutamate : ammonia ligase, EC 6.3.1.2) fromPhaseolus aureus (mung bean) seedlings was purified to homogeneity by ammonium sulphate fractionation, DEAE-cellulose chromatography, Sephadex G-200 gel filtration and affinity chromatography on histidine-Sepharose. The enzyme had a molecular weight of 775,000 ± 25,000. The enzyme consisted of identical subunits with an approximate subunit molecular weight of 50,000. Hyperbolic saturation curves were obtained with the substrates, glutamate, ATP and hydroxylamine.

      Antibody, raised in the rabbit, against mung bean glutamine synthetase, completely inhibited the activity of the enzyme. Preincubation of the enzyme with glutamate and ATP, prior to the addition of the antibody, partially protected the enzyme against inhibition. TheKm values of this enzyme-antibody complex and the native enzyme were identical (glutamate, 2.5mM; ATP, 1 mM; hydroxylamine, 0.5 mM). The Km values of the partially inhibited enzyme (the enzyme pretreated with antibody prior to the addition of substrates) were 2-fold higher than those of the native enzyme. These results suggested that the substrate-induced conformational changes in the enzyme were responsible for the protection against inhibition of the enzyme activity by the antibody.

    • Author Affiliations

       

      S Seethalakshmi1 N Appaji Rao1

      1. Department of Biochemistry, Indian Institute of Science, Bangalore - 560 012

    • Dates

       
      Published
      March 1979
      Manuscript received
      6 November 1978

  • Journal of Biosciences | News

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    • 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

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