• Purification and regulation of aspartate transcarbamylase from germinated mung bean (Vigna radiata) seedlings

    • Fulltext

       

        Click here to view fulltext PDF


      Permanent link:
      https://www.ias.ac.in/article/fulltext/jbsc/006/02/0233-0248

    • Keywords

       

      Aspartate transcarbamylase; mung bean; purification; regulation; hysteresis; association-dissociation

    • Abstract

       

      Aspartate transcarbamylase (EC 2.1.3.2) was purified to homogeniety from germinated mung bean seedlings by treatment with carbamyl phosphate. The purified enzyme was a hexamer with a subunit molecular weight of 20,600. The enzyme exhibited multiple activity bands on Polyacrylamide gel electrophoresis, which could be altered by treatment with carbamyl phosphate or UMP indicating that the enzyme was probably undergoing reversible association or dissociation in the presence of these effectors. The carbamyl phosphate stabilized enzyme did not exhibit positive homotropic interactions with carbamyl phosphate and hysteresis. The enzyme which had not been exposed to carbamyl phosphate showed a decrease in specific activity with a change in the concentration of both carbamyl phosphate and protein. The carbamyl phosphate saturation and UMP inhibition patterns were complex with a maximum and a plateau region. The partially purified enzyme also exhibited hysteresis and the hysteretic response, a function of protein concentration, was abolished by preincubation with carbamyl phosphate and enhanced by preincubation with UMP. All these observations are compatible with a postulation that the enzyme activity may be regulated by slow reversible association-dissociation dependent on the interaction with allosteric ligands

    • Author Affiliations

       

      P V Prasad1 2 N Appaji Rao1

      1. Department of Biochemistry, Indian Institute of Science, Bangalore - 560012, India
      2. Division of Biochemistry, Scripps Clinic and Research Foundation, 10666, North Torrey Pines Road, La Jolla, California - 92037, USA
    • Dates

       
  • Journal of Biosciences | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.