GtfC Enzyme of Geobacillus sp. 12AMOR1 Represents a Novel Thermostable Type of GH70 4,6-α-Glucanotransferase That Synthesizes a Linear Alternating (α1 → 6)/(α1 → 4) α-Glucan and Delays Bread Staling

Evelien M. Te Poele, Stevan E. Van Der Hoek, Anastasia C. Chatziioannou, Gerrit J. Gerwig, Wouter J. Duisterwinkel, Lizette A.A.C.M. Oudhuis, Joana Gangoiti, Lubbert Dijkhuizen, Hans Leemhuis*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)
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Abstract

Starch-acting α-glucanotransferase enzymes are of great interest for applications in the food industry. In previous work, we have characterized various 4,6- and 4,3-α-glucanotransferases of the glycosyl hydrolase (GH) family 70 (subfamily GtfB), synthesizing linear or branched α-glucans. Thus far, GtfB enzymes have only been identified in mesophilic Lactobacilli. Database searches showed that related GtfC enzymes occur in Gram-positive bacteria of the genera Exiguobacterium, Bacillus, and Geobacillus, adapted to growth at more extreme temperatures. Here, we report characteristics of the Geobacillus sp. 12AMOR1 GtfC enzyme, with an optimal reaction temperature of 60 °C and a melting temperature of 68 °C, allowing starch conversions at relatively high temperatures. This thermostable 4,6-α-glucanotransferase has a novel product specificity, cleaving off predominantly maltose units from amylose, attaching them with an (α1 → 6)-linkage to acceptor substrates. In fact, this GtfC represents a novel maltogenic α-amylase. Detailed structural characterization of its starch-derived α-glucan products revealed that it yielded a unique polymer with alternating (α1 → 6)/(α1 → 4)-linked glucose units but without branches. Notably, this Geobacillus sp. 12AMOR1 GtfC enzyme showed clear antistaling effects in bread bakery products.

Original languageEnglish
Pages (from-to)9859-9868
Number of pages10
JournalJournal of Agricultural and Food Chemistry
Volume69
Issue number34
DOIs
Publication statusPublished - 1-Sept-2021

Keywords

  • antistaling
  • maltose
  • NMR spectroscopy
  • thermostable
  • α-glucanotransferase

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