New acidic proteases from Liza aurata viscera: Characterization and application in gelatin production

Biochemical characterization of a semi-purified aspartic protease from sea catfish Bagre panamensis with milk-clotting activity

“…In contrast, the concentrations of 2-mercaptoethanol used here favored acid enzyme activity, with up to an 80% increase in enzyme activity by using 15% 2-mercaptoethanol, relative to the control treatment. Contrary results were observed with acidic proteases from grey mullet (Liza aurata) which are partially inhibited in the presence of mercaptoethanol (Bkhairia et al, 2016). The addition of 5 mM DTT did not affect acid enzyme activity.…”

“…The acid protease of B. panamensis showed the highest specific activity at pH of 2 and 3, with values of 3601 and 3979 U/mg protein, respectively, with no significant differences between them. Similar optimum pH values were recorded for pepsins from Thunnus alalunga (at pH of 1.5-3; Nalinanon et al, 2010) and Liza aurata (at pH of 3; Bkhairia et al, 2016). In contrast, at higher pH levels, the enzyme activity trends to decrease (to pH 5 and 6, remained 34 and 1% of maximum relative activity, respectively), indicating that an alkaline medium brings unfavorable conformational changes in pepsin.…”

“…To evaluate the effect of metal ions on acidic proteolytic activity, aliquots of semi-purified protease enzymes were mixed with 0.2 M glycine-HCl buffer at pH 3.0 containing 5 mM KCl, CaCl 2 , MgCl 2 , FeSO 4 and CuSO 4 , respectively, and incubated for 60 min at 25°C (Bkhairia et al, 2016). Immediately after incubation, acidic enzyme activity was measured as described above.…”

“…Pepsins (EC 3.4.23.1) from marine fish have been used in the preparation of protein hydrolysates (Nalinanon et al, 2011), as well as in the extraction of collagen (Nalinanon et al, 2007) and gelatin (Nalinanon et al, 2008a). To date, there are some reports about the purification and characterization of gastric proteases, mainly pepsins, from marine fish (Bkhairia et al, 2016;Bougatef et al, 2008;Klomklao et al, 2007;Nalinanon et al, 2010). These and others studies report a wide variety of physical, chemical and catalytic properties for purified fish pepsins compared to homologous enzymes from mammals (Zhao et al, 2011).…”

Structure of Hyla rabbit skin gelatin as affected by microwave-assisted extraction

“…The main chains are more than 1,000 residues and the molecular weights are more than 100 kDa. [2] By virtue of attractive advantages such as biocompatibility, hydrophilicity, nontoxicity, gelation, and low cost, [3] gelatin is widely used in food, [4] pharmaceutical, [5] and photographic industries [6] as a gelling agent, stabilizer, thickener, and emulsifier. [7,8] However, the production of gelatin is hampered by the issue of high pollution and long extraction time.…”