Abstract
This study reports on the purification and characterization of a digestive α-amylase from blue crab (Portunus segnis) viscera designated Blue Crab Amylase (BCA). The enzyme was purified to homogeneity by ultrafiltration, Sephadex G-100 gel filtration and Sepharose mono Q anion exchange chromatography, with the final purification fold of 424.02, specific activity of 1390.8 U mg−1 and 27.8% recovery. BCA, showing a molecular weight of approximately 45 kDa, possesses desirable biotechnological features, such as optimal temperature of 50 °C, interesting thermal stability which is enhanced in the presence of starch, high stability towards surfactants (Tween 20, Tween 80 and Triton X-100), high specific activity, quite high storage and broad pH range stability. The enzyme displayed Km and Vmax values, of 7.5 ± 0.25 mg mL−1 and 2000 ± 23 μmol min−1 mg−1 for potato starch, respectively. It hydrolyzed various carbohydrates and produced maltose, maltotriose and maltotetraose as the major end products of starch hydrolysis. In addition, the purified enzyme was successfully utilized for the improvement of the antioxidant potential of oat flour, which could be extended to other cereals. Interestingly, besides its suitability for application in different industrial sectors, especially food industries, the biochemical properties of BCA from the blue crab viscera provide novel features with other marine-derived enzymes and better understanding of the biodegradability of carbohydrates in marine environments, particularly in invasive alien crustaceans.
Highlights
Owing to its vast diversity of organisms and habitats, the marine world is considered a prominent potential source of unique and valuable bioactive compounds, of carbohydrate-active enzymes [1]
This study focuses on a novel digestive α-amylase extraction and purification from the blue crab (Portunus segnis) viscera, as well as its biochemical characterization and application for the improvement of antioxidant potential of oat flour
In order to establish the specific properties of the digestive α-amylase from Portunus segnis (BCA), the crude amylolytic extract of the blue crab visceral waste has been subjected to a series of treatments, each aiming at the subsequent improvement of the purity level
Summary
Owing to its vast diversity of organisms and habitats, the marine world is considered a prominent potential source of unique and valuable bioactive compounds, of carbohydrate-active enzymes [1]. Α-amylases (1,4-α-D-glucan glucanohydrolase, EC 3.2.1.1), which represent about 30% of the whole enzyme market in the world, are endo-acting enzymes belonging to glycoside hydrolase family 13 (GH13) [10,11,12,13,14] Such enzymes catalyze the hydrolysis, in a random fashion, of α-1,4-glycosidic bonds in amylose, amylopectin and starch-related polysaccharides yielding low molecular weight saccharides, including maltodextrins, maltose and glucose molecules. Α-Amylases are known as commercially relevant enzymes for numerous important industrial applications in food (starch liquefaction and saccharification, baking industries, preparation of digestive aids, etc.), textile, detergents, paper, brewing, distilling and pharmaceutical industries [15,16] For such industrial purposes, considerable attention has been focused on the search for low-cost sources for obtaining new α-amylases with improved/novel properties [17,18]
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