期刊
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
卷 137, 期 -, 页码 973-981出版社
ELSEVIER
DOI: 10.1016/j.ijbiomac.2019.07.054
关键词
Pullulanase; CBM68; CBM41; Thermostability; Acidic stability; Catalytic efficiency
资金
- National Natural Science Fundation of China [31701534]
- Tianjin Science & Technology Planning Project [14ZCZDSY00157, 15PTCYSY00020]
- Yantai Marine economy innovation development demonstration project [YHCX-SW-L-201703]
Some specific properties of pullulanases usually have a great deal to do with their specific N-terminal CBMs. This paper focusses on characters of the novel carbohydrate-binding module CBM68 from a thermostable pullulanase PulA. As to reveal its different properties with the common module CBM41/CBM41-X45 (from an acid pullulanase PulB), twelve recombinant pullulanases were constructed and named as Pul-1 similar to Pul-12 respectively. Through comparative analysis of their thermostabilities, pH profiles, and kinetic parameters, some rules have been concluded. Compared with CBM41, CBM68 on the N-terminal of molecules could make pullulanases more thermostable, have higher substrate affinity, and have higher catalytic efficiency. While CBM41 had the advantage on improving the acidic stability of pullulanase comparing with CBM68. X45 could help pullulanases fold properly and has impact to the catalytic domains of pullulanase. The catalytic domain of PulA or PulB played important roles in the optimum pH and catalytic efficiency of pullulanases. Moreover, the optimal combination of CBM41-X45 and the catalytic domain of PulA made Pul-7 have the highest catalytic efficiency (1284.68 mL/mg.s) which was 1.74 times higher than that (737.78 mL/mg.s) of PulA. The characteristics of CBM68, CBM41 and CBM41-X45 revealed in this study would serve as a basis for rational design of pullulanases. (C) 2019 Elsevier B.V. All rights reserved.
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