Improved Hydrolysis of Granular Starches by a Psychrophilic α-Amylase Starch Binding Domain-Fusion

Yu Wang, Yu Tian, Yuyue Zhong, Mohammad Amer Suleiman, Georges Feller, Peter Westh, Andreas Blennow, Marie Sofie Møller*, Birte Svensson*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Degradation of starch granules by a psychrophilic α-amylase, AHA, from the Antarctic bacterium Pseudoalteromonas haloplanktis TAB23 was facilitated by C-terminal fusion to a starch-binding domain (SBD) from either Aspergillus niger glucoamylase (SBDGA) or Arabidopsis thaliana glucan, water dikinase 3 (SBDGWD3) via a decapeptide linker. Depending on the waxy, normal or high-amylose starch type and the botanical source, the AHA-SBD fusion enzymes showed up to 3 times higher activity than AHA wild-type. The SBD-fusion thus increased the density of enzyme attack-sites and binding-sites on the starch granules by up to 5- and 7-fold, respectively, as measured using an interfacial catalysis approach that combined conventional Michaelis-Menten kinetics, with the substrate in excess, and inverse kinetics, having enzyme in excess, with enzyme-starch granule adsorption isotherms. Higher substrate affinity of the SBDGA compared to SBDGWD3 was accompanied by the superior activity of AHA-SBDGA in agreement with the Sabatier principle of adsorption limited heterogenous catalysis.
Original languageEnglish
JournalJournal of Agricultural and Food Chemistry
Pages (from-to)9040-9050
Number of pages11
ISSN0021-8561
DOIs
Publication statusPublished - 2023

Keywords

  • Carbohydrate-binding module
  • Waxy starch
  • Normal starch
  • High-amylose starch
  • Pseudoalteromonas haloplanktis α-amylase
  • Heterogenous catalysis
  • Sabatier principle

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