Identification of the enantiomeric nature of 2-keto-3-deoxy-galactonate in the catabolic pathway of 3,6-anhydro-l-galactose

Eun Ju Yun, Sora Yu, Dong Hyun Kim, Na Jung Park, Jing Jing Liu, Yong Su Jin, Kyoung Heon Kim

Research output: Contribution to journalArticlepeer-review


Abstract: A novel metabolic pathway of 3,6-anhydro-l-galactose (l-AHG), the main sugar component in red macroalgae, was first discovered in the marine bacterium Vibrio sp. EJY3. l-AHG is converted to 2-keto-3-deoxy-galactonate (KDGal) in two metabolic steps. Here, we identified the enantiomeric nature of KDGal in the l-AHG catabolic pathway via stereospecific enzymatic reactions accompanying the biosynthesis of enantiopure l-KDGal and d-KDGal. Enantiopure l-KDGal and d-KDGal were synthesized by enzymatic reactions derived from the fungal galacturonate and bacterial oxidative galactose pathways, respectively. KDGal, which is involved in the l-AHG pathway, was also prepared. The results obtained from the reactions with an l-KDGal aldolase, specifically acting on l-KDGal, showed that KDGal in the l-AHG pathway exists in an l-enantiomeric form. Notably, we demonstrated the utilization of l-KDGal by Escherichia coli for the first time. E. coli cannot utilize l-KDGal as the sole carbon source. However, when a mixture of l-KDGal and d-galacturonate was used, E. coli utilized both. Our study suggests a stereoselective method to determine the absolute configuration of a compound. In addition, our results can be used to explore the novel l-KDGal catabolic pathway in E. coli and to construct an engineered microbial platform that assimilates l-AHG or l-KDGal as substrates. Key points: • Stereospecific enzyme reactions were used to identify enantiomeric nature of KDGal • KDGal in the l -AHG catabolic pathway exists in an l -enantiomeric form • E.

Original languageEnglish (US)
Pages (from-to)7427-7438
Number of pages12
JournalApplied Microbiology and Biotechnology
Issue number24
StatePublished - Dec 2023


  • 2-Keto-3-deoxy-galactonate
  • 3,6-Anhydro-l-galactose
  • Enantiomer
  • Escherichia coli
  • Red macroalgae
  • Stereospecificity

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Biotechnology


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