Characterization of An Indole-3-Acetyl-L-Alanine Hydrolase

• Main Authors: Yun-Bin Huang, 黃允斌
• Other Authors: J.C.Chou
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/21192575063419366055

碩士 === 國立東華大學 === 生物技術研究所 === 93 === Indole-3-acetic acid (IAA) is the most abundant auxin in plants. It involves in all aspects of plant growth and development. The regulation of IAA conjugate formation and hydrolysis is an important component to maintain IAA levels in plants. We want to isolate bacterial strains exhibiting significant IAA-Ala hydrolase activity by using standard enrichment techniques since IAA amino acid conjugate hydrolase identified from plants are not substrate specific and their activity are very low. We used N-acetyl-D,L-Ala as the sole source of carbon and nitrogen to induce IAA-Ala hydrolases, and identified 4 bacterial strains that can produce IAA-Ala hydrolases. They are Arthrobacter ureafaciens C-10, Arthrobacter ureafaciens C-50, Arthrobacter ilicis D-50, Cellulomonas fimi D-100. We chose Arthrobacter ilicis D-50 for further enzymatic analysis. We calculate its Km for IAA-Ala is 5.65 mM by Lineweaver -Burk plot. The optimal pH of this enzyme was between 8.0 and 8.5. Addition of 1 mM CuSO4 and DTT would decrease its activity to 30％ and 0%, respectively. The hydrolase activity was also inhibited by 50％ with 1％ Trition X-100. On the other hand, 1 mM CoCl2 increased the enzyme activity by 50%.