title: Detection and preliminary characterization of extracellular proteolytic activities of the haloalkaliphilic archaeon Natronococcus occultus.
abstract: Extracellular proteolytic activity was detected in the haloalkaliphilic archaeon Natronococcus occultus as the culture reached the stationary growth phase. Proteolytic activity was precipitated with ethanol and subjected to a preliminary characterization. Optimal conditions for activity were attained at 60 degrees C and 1-2 M NaCl or KCl. Gelatin zymography in the presence of 4 M betaine revealed a complex pattern of active species with apparent molecular masses ranging from 50 to 120 kDa. Experiments performed with inhibitors of the various groups of proteases indicated that the extracellular proteolytic enzymes of N. occultus are of the serine type. Individual protein species showed some differences in salt and thermal stability.
authors.affiliation: Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina. studdert@mdp.edu.ar
authors.forename: C A
authors.initials: CA
authors.lastname: Studdert
authors.forename: R E
authors.initials: RE
authors.lastname: De Castro
authors.forename: K H
authors.initials: KH
authors.lastname: Seitz
authors.forename: J J
authors.initials: JJ
authors.lastname: Sánchez
mesh_terms: D001105:Archaea / Q000737:chemistry / Q000201:enzymology* / Q000254:growth & development; D019843:Archaeal Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D004795:Enzyme Stability / Q000187:drug effects; D005110:Extracellular Space / Q000201:enzymology; D006868:Hydrolysis / Q000187:drug effects; D011189:Potassium Chloride / Q000378:metabolism; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D012965:Sodium Chloride / Q000378:metabolism; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D015842:Serine Proteinase Inhibitors; D012965:Sodium Chloride; D011189:Potassium Chloride; D012697:Serine Endopeptidases