title: Biochemical characterization of a halophilic, alkalithermophilic protease from Alkalibacillus sp. NM-Da2.
abstract: An extracellular, halophilic, alkalithermophilic serine protease from the halo-alkaliphilic Alkalibacillus sp. NM-Da2 was purified to homogeneity by ethanol precipitation and anion-exchange chromatography. The purified protease was a monomeric enzyme with an approximate molecular mass of 35 kDa and exhibited maximal activity at 2.7 M NaCl, pH55 °C9 and 56 °C. The protease showed great temperature stability, retaining greater than 80 % of initial activity after 2 h incubation at 55 °C. The protease was also extremely pH tolerant, retaining 80 % of initial activity at pH55 °C10.5 after 30 min incubation. Protease hydrolyzed complex substrates, displaying activity on yeast extract, tryptone, casein, gelatin and peptone. Protease activity was inhibited at casein concentrations greater than 1.2 mg/mL. The enzyme was stable and active in 40 % (v/v) solutions of isopropanol, ethanol and benzene and was stable in the presence of the polysorbate surfactant Tween 80. Activity was stimulated with the oxidizing agent hydrogen peroxide. Inhibition with phenyl methylsulfonylfluoride indicates it is a serine protease. Synthetic saline wastewater treated with the protease showed 50 % protein removal after 5 h. Being halophilic, alkaliphilic and thermophilic, in addition to being resistant to organic solvents, this protease has potential for various applications in biotechnological and pharmaceutical industries.
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Suez Canal University, Ismailia, 41522, Egypt.
authors.forename: Asmaa R
authors.initials: AR
authors.lastname: Abdel-Hamed
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Suez Canal University, Ismailia, 41522, Egypt.
authors.forename: Dina M
authors.initials: DM
authors.lastname: Abo-Elmatty
authors.affiliation: Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.
authors.forename: Juergen
authors.initials: J
authors.lastname: Wiegel
authors.affiliation: Department of Biochemistry, Faculty of Pharmacy, Suez Canal University, Ismailia, 41522, Egypt. noha_mesbah@pharm.suez.edu.eg.
authors.forename: Noha M
authors.initials: NM
authors.lastname: Mesbah
mesh_terms: D001406:Bacillaceae / Q000201:enzymology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004795:Enzyme Stability; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D054712:Salinity; D057057:Serine Proteases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D013450:Sulfones / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; C005109:methanesulfonyl fluoride; D006861:Hydrogen Peroxide; D057057:Serine Proteases
keywords: Alkaliphilic; Extremophile; Halophilic; Protease; Thermophilic; Wadi An Natrun