title: Purification and characterization of a thermostable, haloalkaliphilic extracellular serine protease from the extreme halophilic archaeon Halogeometricum borinquense strain TSS101.
abstract: A novel haloalkaliphilic, thermostable serine protease was purified from the extreme halophilic archaeon, Halogeometricum borinquense strain TSS101. The protease was isolated from a stationary phase culture, purified 116-fold with 18% yield and characterized biochemically. The molecular mass of the purified enzyme was estimated to be 86 kDa. The enzyme showed the highest activity at 60 degrees C and pH 10.0 in 20% NaCl. The enzyme had high activity over the pH range from 6.0 to 10.0. Enzymatic activity was strongly inhibited by 1 mM phenyl methylsulfonyl fluoride, but activity was increased 59% by 0.1% cetyltrimethylammonium bromide. The enzyme exhibited relatively high thermal stability, retaining 80% of its activity after 1 h at 90 degrees C. Thermostability increased in the presence of Ca2+. The stability of the enzyme was maintained in 10% sucrose and in the absence of NaCl.
authors.affiliation: Department of Biochemistry, Gulbarga University, Gulbarga-585 106, Karnataka, India.
authors.forename: Malashetty
authors.initials: M
authors.lastname: Vidyasagar
authors.forename: S
authors.initials: S
authors.lastname: Prakash
authors.forename: Carol
authors.initials: C
authors.lastname: Litchfield
authors.forename: K
authors.initials: K
authors.lastname: Sreeramulu
mesh_terms: D002118:Calcium / Q000494:pharmacology; D006216:Halobacteriaceae / Q000201:enzymology*; D012697:Serine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D012965:Sodium Chloride; D012697:Serine Endopeptidases; D002118:Calcium