Biochemical studies of novel aspartate racemase from

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K15320
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Aquatic life science
• Research Institution: Hiroshima University
• Principal Investigator: Koyama Hiroki 広島大学, 統合生命科学研究科, 助教 (20746515)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: D-アスパラギン酸 / アスパラギン酸ラセマーゼ / スルメイカ / 視神経節

Outline of Final Research Achievements

The concentrations of L and D-aspartate (Asp) in optic ganglion of Japanese common squid were 1.83μmol/g tissue and 1.57μmol/g tissue, respectively. It indicated that the 46.2% of total Asp was D-form.
We also examined the aspartate racemase (AspRase) activity from L-Asp to D-Asp by using the crude enzyme extracted from optic ganglion. It was found that the AspRase activity was 28nmol/mg・h. This activity was weaker than that of ark shell AspRase.
In order to isolate the AspRase gene by expression cloning, we tried to construct cDNA library. However, we could not obtain the enough amount of clone number for expression cloning. Therefore, the construction of cDNA library for expression cloning is future work.

Free Research Field

水産化学

Academic Significance and Societal Importance of the Research Achievements

神経系に存在するD-アスパラギン酸（D-Asp）は神経伝達物質としての働きが示唆されているが、生合成経路を含めその詳細については不明な点が多い。本研究ではスルメイカ視神経節において発現するD-Aspの生合成酵素であるアスパラギン酸ラセマーゼ（AspRase）遺伝子の単離を試みた。単離には成功しなかったが、視神経節由来の粗酵素液からはAspRase活性が検出されるなどの観点から、神経系のD-Asp機能解明にはスルメイカが試料として適していることが強く示唆された。