title: Purification and characterization of a thermostable keratinolytic serine alkaline proteinase from Streptomyces sp. strain AB1 with high stability in organic solvents.
abstract: A keratinolytic alkaline proteinase (KERAB) was isolated from Streptomyces sp. strain AB1. Based on MALDI-TOF mass spectrometry analysis, the purified enzyme is a monomer with a molecular mass of 29850.17Da. The NH(2)-terminal sequence of the enzyme was determined to be TQANPPSWGLDDIDQTAL. This keratinase was completely inhibited by phenylmethanesulfonyl fluoride (PMSF) and diiodopropyl fluorophosphates (DIFP), which suggests that it belongs to the serine protease family. Using keratin azure as a substrate, the optimum pH and temperature values for keratinase activity were pH 11.5 and 75 degrees C, respectively. This keratinase was stable between 30 and 60 degrees C and pH 4 and 11 for 4 and 96 h, respectively, and thermoactivity and thermostability were enhanced in the presence of 5 mM Mg(2+). Its catalytic efficiency was higher than those of SAPB-L31I/T33S/N99Y, nattokinase and subtilisin Carlsberg. KERAB exhibited stability to detergents and high resistance against organic solvents and was able to degrade feathers completely. These properties make KERAB a potential candidate for future applications in detergent formulations, dehairing during leather processing, and non-aqueous peptide biocatalysis.
authors.affiliation: Laboratoire d'Enzymes et de Métabolites des Procaryotes (LEMP), Centre de Biotechnologie de Sfax (CBS), B.P. 1177, Route de Sidi Mansour Km 6, 3018 Sfax, Tunisia. bassem.jaouadi@yahoo.fr
authors.forename: Bassem
authors.initials: B
authors.lastname: Jaouadi
authors.forename: Badis
authors.initials: B
authors.lastname: Abdelmalek
authors.forename: Djamila
authors.initials: D
authors.lastname: Fodil
authors.forename: Fatma Zohra
authors.initials: FZ
authors.lastname: Ferradji
authors.forename: Hatem
authors.initials: H
authors.lastname: Rekik
authors.forename: Nedia
authors.initials: N
authors.lastname: Zaraî
authors.forename: Samir
authors.initials: S
authors.lastname: Bejar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003902:Detergents / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D005241:Feathers; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D006868:Hydrolysis / Q000187:drug effects; D007477:Ions; D007700:Kinetics; D008969:Molecular Sequence Data; D009930:Organic Chemicals / Q000737:chemistry*; D010447:Peptide Hydrolases / Q000737:chemistry / Q000302:isolation & purification*; D010455:Peptides / Q000494:pharmacology; D010802:Phylogeny; D057057:Serine Proteases / Q000737:chemistry / Q000302:isolation & purification*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry*; D013302:Streptomyces / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity / Q000187:drug effects; D013696:Temperature
chemical_list: D003902:Detergents; D007477:Ions; D009930:Organic Chemicals; D010455:Peptides; D015842:Serine Proteinase Inhibitors; D012997:Solvents; D010447:Peptide Hydrolases; D057057:Serine Proteases; C035855:keratinase