Functional analysis of food proteins and food-related enzymes.

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04909
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Applied biochemistry
• Research Institution: Kyoto University
• Principal Investigator: Mikami Bunzo 京都大学, 農学研究科, 教授 (40135611)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 構造生物学 / タンパク質工学 / 酵素工学 / X線結晶構造解析 / アミラーゼ / プルラナーゼ / プロテイングルタミナーゼ

Outline of Final Research Achievements

Proteins and enzymes can work through their conformational changes during interaction with substrate and ligands. These conformational changes can be detected by X-ray crystal analysis. But sometimes it is difficult to study about the conformational change owing to bad packing in the crystal lattice. It is also affected by “freezing of protein crystals” and cryo-protectants that usually interact with protein active site. We have to use non-freezing structure especially to observe the effect of pH. In the present work, I have studied about the function of food-related enzymes such as beta-amylase, pullulanase and protein glutaminase by X-ray crystal analysis with freezing and non-freezing (capillary) methods. I could get the fine structure changes in the active site of beta-amylase/substrate complexes caused by pH. The functions of pullulanase and protein glutaminase were also studied using mutant and complex crystals.

Free Research Field

構造生物学

Academic Significance and Societal Importance of the Research Achievements

今までに数多くのタンパク質や酵素の構造がX線結晶構造解析によって決定されているが、その働きを理解するためには、実際にタンパク質や酵素が働くところ、つまりタンパク質の構造変化を正しく捕らえる必要がある。本研究では、凍結法のみならず非凍結状態での構造解析を行うことによって食品加工に関連する酵素（β－アミラーゼ、プルラナーゼおよびプロテイングルタミナーゼ）の今まで知られていなかった機能を明らかにすることができた。酵素の働きを正しく理解することによって、より優れた酵素の設計が可能になる。