Molecular basis and functional modulation of carbohydrate epimerases and isomerases useful for carbohydrate conversion

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05388
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38030:Applied biochemistry-related
• Research Institution: Hokkaido University
• Principal Investigator: Wataru Saburi 北海道大学, 農学研究院, 准教授 (00598089)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: cellobiose 2-epimerase / mannose 2-epimerase / AGE superfamily / carbohydrate / mannose / cellobiose

Outline of Final Research Achievements

Carbohydrate epimerase/isomerases are essential for the diversification and sophistication of enzymatic synthesis of carbohydrates. In this study, two carbohydrate epimerases, cellobiose 2-epimerase (CE) and mannose 2-epimerase (ME) were studied: CE, the molecular basis of the reaction specificity; ME, the structure-function relationship and the development of practical enzymes with high specific activity. In CE, the four α-helices at the N-terminal end of the catalytic domain were shown to contain structures important for isomerase activity. Additionally, the substitution of a small amino acid for Asn, involved in the formation of a hydrogen bond with sugar at reducing end, was shown to drastically enhance the reaction specificity for isomerization. Although a highly active mutant enzyme of ME was not obtained, the crystal structure of ME was successfully determined and structures important for substrate specificity was clarified.

Free Research Field

生物化学

Academic Significance and Societal Importance of the Research Achievements

本研究では糖質の合成の多様化に貢献する糖質異性化酵素が示す反応特異性や基質特異性に関する分子機構の一端を解き明かすことができた．マンノース2-エピメラーゼの構造は本研究により初めて明らかにされたものであり，本酵素の基質特異性の分子基盤が解明されたことの学術的意義は大きい．また本研究で得られた知見は糖質のより高効率な合成酵素の開発や，合成される糖質の大量合成・機能解析へとつながるものと考えられ，機能性糖質の開発など応用に関する波及効果も大きく，社会的意義も大きいと考えられる．