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Bifunctional enhancement of a β-glucanase-xylanase fusion enzyme by optimization of peptide linkers


The flexible peptides (GGGGS)n (n ≤ 3), the α-helical peptides (EAAAK)n (n ≤ 3) and two other peptides were used as linkers to construct bifunctional fusions of β-glucanase (Glu) and xylanase (Xyl) for improved catalytic efficiencies of both moieties. Eight Glu-Xyl fusion enzymes constructed with different linkers were all expressed as the proteins of ca. 46 kDa in Escherichia coli BL21 and displayed the activities of both β-glucanase and xylanase. Compared to all the characterized fusions with the parental enzymes, the catalytic efficiencies of the Glu and Xyl moieties were equivalent to 304–426% and 82–143% of the parental ones, respectively. The peptide linker (GGGGS)2 resulted in the best fusion, whose catalytic efficiency had a net increase of 326% for the Glu and of 43% for the Xyl. The two moieties of a fusion with the linker (EAAAK)3 also showed net increases of 262 and 31% in catalytic efficiency. Our results highlight, for the first time, the enhanced bifunctional activities of the Glu-Xyl fusion enzyme by optimizing the peptide linkers to separate the two moieties at a reasonable distance for beneficial interaction.

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Chang HC (Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany) is thanked for providing the nucleotide sequences of α-helical peptide linkers. This study was supported jointly by the Ministry of Science and Technology of China (2007DFA3100), the Natural Science Foundation of China (30571250), the Ministry of Education of China (IRT0535), and Zhejiang R&D Program (2007C12035).

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Correspondence to Ming-Guang Feng.

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Lu, P., Feng, M. Bifunctional enhancement of a β-glucanase-xylanase fusion enzyme by optimization of peptide linkers. Appl Microbiol Biotechnol 79, 579–587 (2008).

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  • Bifunctional fusion enzyme
  • β-glucanase
  • Xylanase
  • Peptide linker optimization