Diversification of carbohydrate phosphorylases

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K22263
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 38:Agricultural chemistry and related fields
• Research Institution: Hokkaido University
• Principal Investigator: MORI Haruhide 北海道大学, 農学研究院, 教授 (80241363)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: 酵素機能 / 酵素利用 / 糖質生産

Outline of Final Research Achievements

To develop the enzymatic production of carbohydrates, phosphorylases were investigated in this study. A new activity, solabiose phosphorylase, was found. A possible metabolism involving the enzyme and a practical enzymatic synthesis of solabiose using this enzyme were shown.
Maltoside phosphorylase, as a member of starch-hydrolyzing enzyme family, was analysed intensively. Kinetic analysis revealed that the reaction followed the two-steps reaction, and phosphorolysis, transglycosylation, and hydrolysis occurred through competitive binding of the second substrates on the glycosyl enzyme intermediate. Significant change of the proportion of the three activities caused by mutations in possible binding residues suggested appropriate residues for the activities. Using the enzyme activity, insoluble α-glucans were produced though extension of their branched chains.

Free Research Field

応用生物化学

Academic Significance and Societal Importance of the Research Achievements

糖質には，食品素材として味やエネルギーに加え，各種健康調節機能をも示し，またバイオ素材等として利用されるなど，広範な機能性化合物がある．多種多様の糖質合成は，その構成糖や結合様式の改変により行われる．酵素利用による糖質合成は，安価で大量の生産に適しており，加リン酸分解酵素（加リン酸分解の逆反応）も利用される．本研究成果として，新規酵素が見いだされて特定2糖の効率的合成が可能となった．α-グルカンの新たな加工法も提唱された．加えて，得られた加リン酸分解酵素の活性寄与構造に関する情報は，類似構造を有する多様な加水分解酵素の加リン酸分解活性付与に向けた酵素分子加工の基盤的知見となる．