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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jbsc/002/03/0211-0225

    • Keywords

       

      Phaseolus aureus ; nucleotide pyrophosphatase; regulation; desensitization; conformational changes; circular dichroism; optical rotatory dispersion

    • Abstract

       

      A homogenous and crystalline form of nucleotide pyrophosphatase (EC 3.6.1.9) fromPhaseolus aureus (mung bean) seedlings was used for the study of the regulation of enzyme activity by adenine nucleotides. The native dimeric form of the enzyme had a helical content of about 65% which was reduced to almost zero values by the addition of AMP. In addition to this change in the helical content, AMP converted the native dimer to a tetramer. Desensitization of AMP regulation, without an alteration of the molecular weight, was achieved either by reversible denaturation with 6 M urea or by passage through a column of Blue Sepharose but additionofp-hydroxymercuribenzoate desensitized the enzyme by dissociating the native dimer to a monomer. The changes in the quaternary structure and conformation of the enzyme consequent to AMP interaction or desensitization were monitored by measuring the helical content, EDTA inactivation and Zn2+ reactivation, stability towards heat denaturation, profiles of urea denaturation and susceptibility towards proteolytic digestion. Based on these results and our earlier work on this enzyme, we propose a model for the regulation of the mung bean nucleotide pyrophosphatase by association-dissociation and conformational changes. The model emphasizes that multiple mechanisms are operative in the desensitization of regulatory proteins.

    • Author Affiliations

       

      A R Venugopala Reddy1 2 C V Balakrishnan1 2 3 J Sobhanaditya1 2 S D Ravindranath1 2 4 V S Ananthanarayanan1 2 N Appaji Rao1 2

      1. Department of Biochemistry, and Molecular Biophysics Unit, Indian Institute of Science, Bangalore - 560 012
      2. Department of Biochemistry, Memorial University of Newfoundland St. John’s, Newfoundland, Canada
      3. Division of Neurology, Department of Medicine, Duke University Medical Centre, Durham, North Carolina, USA
      4. Department of Biochemistry, Toklai Experimental Station, Jorhat, Assam - 785 008, India

    • Dates

       
      Published
      September 1980
      Manuscript received
      26 May 1980
      Manuscript revised
      18 August 1980

  • 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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    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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