An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was express...An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities.展开更多
Red algae represents an important marine bioresource.One high-value utilization of red algae is the production of agarooligosaccharides which have many positive biological effects.However,the lack of an efficient prod...Red algae represents an important marine bioresource.One high-value utilization of red algae is the production of agarooligosaccharides which have many positive biological effects.However,the lack of an efficient production route seriously limits the application of agaro-oligosaccharides.In this study,we established a green route that combines chemical liquefaction and enzymatic catalysis for the efficient production of agaro-oligosaccharides,and we used the production of neoagarotetraose(NA4)as an example.Agarose(150 g L^−1)liquefaction by citric acid was controlled with respect to two targets:a 100%liquefaction rate and a high average degree of polymerization(>4)of the liquesced agaro-oligosaccharides,which were then catalyzed byβ-agarase into an oligosaccharides mixture with a high concentration of NA4(30.8 g L^−1)in a 1-L reaction volume.After purification,we obtained 25.5 g of NA4 with a purity of 92%.This work establishes an easy route for the efficient production of pure agaro-oligosaccharides from agarose.展开更多
基金The Natural Science Foundation of Fujian Province of China under contract No.2016J01162the Program for New Century Excellent Talents in Fujian Province University,China under contract No.B15139
文摘An agarase gene containing 1 302 bp was cloned from Microbulbifer sp. AG1. It encoded a mature protein of 413 amino acids plus a 20-residue signal peptide. The recombinant enzyme without the signal peptide was expressed and purified from Escherichia coli BL21(DE3). When agarose was used as a substrate, the optimal temperature and pH for the enzyme were 60℃ and 7.5, respectively. The recombinant agarase showed excellent thermostability with 67% and 19% of residual activities after incubation at 50℃ and 60℃ for 1 h, respectively.Except SDS, the recombinant agarase had a relatively good resistance against the detected inhibitors, detergents and urea denaturant. Thin layer chromatography analysis and enzyme assay using p-nitrophenyl-α/β-Dgalactopyranoside revealed that the recombinant agarase was a β-agarase that degraded agarose into neoagarotetraose as the main end product. The enzymatic hydrolysis products with different degree of polymerization exhibited the antioxidant activities.
基金This work was supported by the National Key R&D Program of China(No.2018YFC0311200)the Fundamental Research Funds for the Central Universities(No.201941002)the Taishan Scholars Project(No.tsqn201812020).
文摘Red algae represents an important marine bioresource.One high-value utilization of red algae is the production of agarooligosaccharides which have many positive biological effects.However,the lack of an efficient production route seriously limits the application of agaro-oligosaccharides.In this study,we established a green route that combines chemical liquefaction and enzymatic catalysis for the efficient production of agaro-oligosaccharides,and we used the production of neoagarotetraose(NA4)as an example.Agarose(150 g L^−1)liquefaction by citric acid was controlled with respect to two targets:a 100%liquefaction rate and a high average degree of polymerization(>4)of the liquesced agaro-oligosaccharides,which were then catalyzed byβ-agarase into an oligosaccharides mixture with a high concentration of NA4(30.8 g L^−1)in a 1-L reaction volume.After purification,we obtained 25.5 g of NA4 with a purity of 92%.This work establishes an easy route for the efficient production of pure agaro-oligosaccharides from agarose.
