κ-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by κ-carrageenase is safe and controllable. Therefore, κ-carrageenases have captured more and more attentions. In this stu...κ-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by κ-carrageenase is safe and controllable. Therefore, κ-carrageenases have captured more and more attentions. In this study, a κ-carrageenase encoding gene, cgk X, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. Cgk X is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with Cgk X of Pseudoalteromonas κ-carrageenase; however, the recombinant Cgk X showed different biochemical characteristics. The recombinant enzyme was most active at p H 7.0 and 55℃ in the presence of 300 mmol L^(^(-1))Na Cl. It was stable in a broad range of acidity ranging from p H 3.0 to p H 10.0 when temperature was below 40℃. More than 80% of its activity was maintained after being incubated at p H 3.6–10.0 and 4℃ for 24 h. Cgk X retained more than 90% of activity after being incubated at 40℃ for 1 h. EDTA and SDS(1 mmol L^(-1)) did not inhibit its activity. Cgk X hydrolyzed κ-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that Cgk X is applicable to both κ-carrageenan oligosaccharide production and κ-carrageenase structure-function research.展开更多
基金supported by the National High-Tech R&D Program(No.2011AA090703)the National Natural Science Foundation of China(No.31070712)the Special Fund for Marine Scientific Research in the Public Interest(Nos.201105027 and 201005024)
文摘κ-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by κ-carrageenase is safe and controllable. Therefore, κ-carrageenases have captured more and more attentions. In this study, a κ-carrageenase encoding gene, cgk X, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. Cgk X is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with Cgk X of Pseudoalteromonas κ-carrageenase; however, the recombinant Cgk X showed different biochemical characteristics. The recombinant enzyme was most active at p H 7.0 and 55℃ in the presence of 300 mmol L^(^(-1))Na Cl. It was stable in a broad range of acidity ranging from p H 3.0 to p H 10.0 when temperature was below 40℃. More than 80% of its activity was maintained after being incubated at p H 3.6–10.0 and 4℃ for 24 h. Cgk X retained more than 90% of activity after being incubated at 40℃ for 1 h. EDTA and SDS(1 mmol L^(-1)) did not inhibit its activity. Cgk X hydrolyzed κ-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that Cgk X is applicable to both κ-carrageenan oligosaccharide production and κ-carrageenase structure-function research.
