title: Efficient expression and purification of recombinant glutaminase from Bacillus licheniformis (GlsA) in Escherichia coli.
abstract: Glutaminase or L-glutamine aminohydrolase (EC 3.5.1.2) is an enzyme that catalyzes the formation of glutamic acid and ammonium ion from glutamine. This enzyme functions in cellular metabolism of every organism by supplying nitrogen required for the biosynthesis of a variety of metabolic intermediates, while glutamic acid plays a role in both sensory and nutritional properties of food. So far there have been only a few reports on cloning, expression and characterization of purified glutaminases. Microbial glutaminases are enzymes with emerging potential in both the food and the pharmaceutical industries. In this research a recombinant glutaminase from Bacillus licheniformis (GlsA) was expressed in Escherichia coli, under the control of a ptac promoter. The recombinant enzyme was tagged with decahistidine tag at its C-terminus and could be conveniently purified by one-step immobilized metal affinity chromatography (IMAC) to apparent homogeneity. The enzyme could be induced for efficient expression with IPTG, yielding approximately 26,000 units from 1-l shake flask cultures. The enzyme was stable at 30°C and pH 7.5 for up to 6h, and could be used efficiently to increase glutamic acid content when protein hydrolysates from soy and anchovy were used as substrates. The study demonstrates an efficient expression system for the production and purification of bacterial glutaminase. In addition, its potential application for bioconversion of glutamine to flavor-enhancing glutamic acid has been demonstrated.
authors.affiliation: Food Protein Research Unit, School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
authors.forename: Sornchai
authors.initials: S
authors.lastname: Sinsuwan
authors.forename: Jirawat
authors.initials: J
authors.lastname: Yongsawatdigul
authors.forename: Suchintana
authors.initials: S
authors.lastname: Chumseng
authors.forename: Montarop
authors.initials: M
authors.lastname: Yamabhai
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics*; D018698:Glutamic Acid / Q000378:metabolism; D005972:Glutaminase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011492:Protein Hydrolysates; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D011492:Protein Hydrolysates; D011993:Recombinant Fusion Proteins; D018698:Glutamic Acid; D006639:Histidine; C492196:GlsA protein, bacteria; D005972:Glutaminase