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    • Keywords


      Bivalent metals; kinetic behavior; MALDI-TOF; purification; & beta; -galactosidase

    • Abstract


      β-Galactosidase is a metal-activated enzyme, which breaks down the glucosidic bond of lactose and produces glucose andgalactose. Among several commercial applications, preparation of lactose-free milk has gained special attention. Thepresent objective is to demonstrate the activity kinetics of β-galactosidase purified from a non-pathogenic bacteriumArthrobacter oxydans SB. The enzyme was purified by DEAE-cellulose and Sephadex G-100 column chromatography. Thepurity of the protein was checked by high-performance liquid chromatography (HPLC). The purified enzyme of molecularweight ~95 kDa exhibited specific activity of 137.7 U mg-1 protein with a purification of 11.22-fold and yield 12.42 %.The exact molecular weight (95.7 kDa) of the purified protein was determined by MALDI-TOF. Previously, most of thestudies have used Mg+2 as a cofactor of β- galactosidase. In this present investigation, we have checked the kineticbehavior of the purified β-galactosidase in presence of several bivalent metals. Lowest Km with highest substrate (orthonitrophenyl-

      β-galactoside or ONPG) affinity was measured in presence of Ca2+ (42.45 μM ONPG). However, our resultsdemonstrated that Vmax was maximum in presence of Mn?2 (55.98 μM ONP produced mg-1 protein min-1), followed byFe+2, Zn+2, Mg+2, Cu+2 and Ca+2. A large number of investigations reported Mg?2 as potential co factor for β-galacosidase.However, β-galactosidase obtained from Arthrobacter oxydans SB has better activity in the presence of Mn+2or Fe2+.

    • Author Affiliations



      1. Department of Zoology, Visva-Bharati University, Santiniketan 731 235, India
      2. Department of Biochemistry, University of Calcutta, Kolkata 700 019, India
      3. Center for Nature Conservation and Biosafety (CNCB Pvt. Ltd.), Cuttack, Odisha 754 132, India
      4. Department of Zoology, Sidho Kanho Birsha University, Purulia 723 104, India
    • Dates

  • Journal of Biosciences | News

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