Additional salt bridges improve the thermostability of 1,4-α-glucan branching enzyme

Xiaofeng Ban, Jing Wu, Bhalerao Kaustubh, Pratik Lahiri, Abhishek S. Dhoble, Zhengbiao Gu, Caiming Li, Li Cheng, Yan Hong, Yi Tong, Zhaofeng Li

Research output: Contribution to journalArticlepeer-review


The 1,4-α-glucan branching enzyme from Geobacillus thermoglucosidans STB02 (GtGBE, EC does not possess the thermostability required by modified starch industry. To increase its thermostability, a rational design strategy was used to introduce additional salt bridges into GtGBE. The strategy involved in mutation of individual residues to form “local” two-residue salt bridges. Accordingly, five of local salt bridges (Q231R-D227, Q231K-D227, T339E-K335, T339D-K335, and I571D-R569 mutants) were separately introduced into GtGBE. The half-times of these mutants at 60 °C were 17% to 51% longer than that of wild-type. Subsequently, these two-residue salt bridges were extended to form salt bridge networks (Q231R/K-D227-D131H, T339D/E-K335-I291H, and I571D-R569-R617H mutants). Among these mutants, except I571D-R569-R617H, the half-times of Q231R/K-D227-D131H, T339D/E-K335-I291H mutants at 60 °C were 15%, 17%, 21% and 17% longer than those of the corresponding two-residue salt bridges, respectively. The results showed that design and introduction of salt bridges improves enzyme thermostability in GtGBE.

Original languageEnglish (US)
Article number126348
JournalFood chemistry
StatePublished - Jun 30 2020


  • 1,4-α-glucan branching enzyme
  • Salt bridge
  • Structural bioinformatics
  • Thermostability

ASJC Scopus subject areas

  • Analytical Chemistry
  • Food Science


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