title: A temperature and salt-tolerant L-glutaminase from gangotri region of uttarakhand himalaya: enzyme purification and characterization.
abstract: Purification and characterization of halotolerant, thermostable alkaline L-glutaminase from a Bacillus sp. LKG-01 (MTCC 10401), isolated from Gangotri region of Uttarakhand Himalaya, is being reported in this paper. Enzyme has been purified 49-fold from cell-free extract with 25% recovery (specific activity 584.2 U/mg protein) by (NH₄)₂SO₄ precipitation followed by anion exchange chromatography and gel filtration. Enzyme has a molecular weight of 66 kDa. L-Glutaminase is most active at pH 11.0 and stable in the pH range 8.0-11.0. Temperature optimum is 70 °C and is completely stable after 3 h pre-incubation at 50 °C. Enzyme reflects more enhanced activity with 1-20% (w/v) NaCl, which is further reduced to 80% when NaCl concentration was increased up to 25%. L-Glutaminase is almost active with K⁺, Zn²⁺, and Ni²⁺ ions and K(m) and V(max) values of 240 μM and 277.77 ± 1.1 U/mg proteins, respectively. Higher specific activity, purification fold, better halo-tolerance, and thermostability would make this enzyme more attractive for food fermentation with respect to other soil microbe derived L-glutaminase reported so far.
authors.affiliation: Department of Biochemistry, Sardar Bhagwan Singh PG Institute of Biomedical Sciences and Research, Balawala, Dehradun 248161, India.
authors.forename: Lokendra
authors.initials: L
authors.lastname: Kumar
authors.forename: Balvinder
authors.initials: B
authors.lastname: Singh
authors.forename: Dilip Kumar
authors.initials: DK
authors.lastname: Adhikari
authors.forename: Joydeep
authors.initials: J
authors.lastname: Mukherjee
authors.forename: Debashish
authors.initials: D
authors.lastname: Ghosh
mesh_terms: D000645:Ammonium Sulfate / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005972:Glutaminase / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007194:India; D007700:Kinetics; D008970:Molecular Weight; D010802:Phylogeny; D055049:Salt Tolerance; D012965:Sodium Chloride
chemical_list: D001426:Bacterial Proteins; D012965:Sodium Chloride; D005972:Glutaminase; D000645:Ammonium Sulfate