title: Digestive alkaline proteases from thornback ray (Raja clavata): Characteristics and applications.
abstract: This study describes the characterization of a crude protease extract from thornback ray (Raja clavata) and its evaluation in liquid detergent and in deproteinizattion of shrimp waste. At least five clear caseinolytic proteases bands were observed in a zymogram. The crude protease showed optimum activity at pH 8.0 and 50 °C, and it was highly stable over pH range from 8.0 to 11.0. Proteolytic enzymes were very stable in non-ionic surfactants and in the presence of oxidizing agents, maintaining 70% of their activity after incubation for 1 h at 30 °C in the presence of 1% sodium perborate. In addition, they showed high stability and compatibility with various liquid laundry-detergents available in the Tunisian market. The crude extract retained 100% of its activity after preincubation for 60 min at 30 °C in the presence of Nadhif Perfect, Textil and Carrefour laundry detergents. Further, proteases from R. clavata viscera were used for shrimp waste deproteinization in the process of chitin preparation. The percent of protein removal after 3 h hydrolysis at 45 °C with an enzyme/substrate ratio of 30 U/mg of proteins was 74%. These results suggest that enzymatic deproteinization of shrimp wastes by fish endogenous alkaline proteases could be applicable to the chitin production process.
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia. Electronic address: lassouedimen@yahoo.fr.
authors.forename: Imen
authors.initials: I
authors.lastname: Lassoued
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Sawssen
authors.initials: S
authors.lastname: Hajji
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Samiha
authors.initials: S
authors.lastname: Mhamdi
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Mourad
authors.initials: M
authors.lastname: Jridi
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Bayoudh
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Barkia
authors.affiliation: Laboratory of Enzyme Engineering and Microbiology, University of Sfax, National Engineering School of Sfax, B.P. 1173, 3038 Sfax, Tunisia.
authors.forename: Moncef
authors.initials: M
authors.lastname: Nasri
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D002686:Chitin / Q000737:chemistry; D003902:Detergents / Q000494:pharmacology; D010450:Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D016877:Oxidants / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D012860:Skates, Fish / Q000378:metabolism*; D013379:Substrate Specificity; D013501:Surface-Active Agents / Q000494:pharmacology; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D003902:Detergents; D007477:Ions; D008670:Metals; D016877:Oxidants; D011480:Protease Inhibitors; D013501:Surface-Active Agents; D002686:Chitin; D010450:Endopeptidases; C087822:alkaline protease
keywords: Alkaline proteases; Chitin; Liquid laundry detergent