Inactivation of an aminoaldehyde dehydrogenase is responsible for fragrance in rice
Inactivation of an aminoaldehyde dehydrogenase is responsible for fragrance in rice
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DOI：
10.1007/s11103-008-9381-x
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发表时间：
2008-11-01
影响因子：
5.1
通讯作者：
Henry, Robert J.
中科院分区：
文献类型：
--
作者：
Bradbury, Louis M. T.;Gillies, Susan A.;Henry, Robert J.
水稻（Oryza sativa）有两个甜菜碱醛脱氢酶同源物，BAD 1和BAD 2，分别编码于第4和第8染色体上。BAD 2负责香米的特征香气。分离BAD 1和BAD 2的互补DNA克隆并在E.杆菌BAD 2在pH 10下具有最佳活性，对N-乙酰基-γ-氨基丁醛（NAGABald）几乎没有亲和力，Km约为10 mM，对γ-胍基丁醛（GGBald）和甜菜碱醛（bet-ald）具有中等亲和力，Km值分别约为260 μ M和63 μ M。用γ-氨基丁醛（GABald）观察到约9 μ M的较低Km，表明BAD 2在体内对该底物具有较高的亲和力。在染色体4上编码的酶BAD 1在pH 9.5下具有最佳活性，对bet-ald显示出很小或没有亲和力，Km为3 mM，对GGBald、NAGABald和GABald具有中等亲和力，Km值分别为约545、420和497 μ M。BAD 1的半衰期大约是BAD 2的两倍。我们讨论了这些研究结果的影响香米和茉莉香米的香味产生的途径和潜在的水稻积累的甜菜碱。
Rice (Oryza sativa) has two betaine aldehyde dehydrogenase homologs, BAD1 and BAD2, encoded on chromosome four and chromosome eight respectively. BAD2 is responsible for the characteristic aroma of fragrant rice. Complementary DNA clones of both BAD1 and BAD2 were isolated and expressed in E. coli. BAD2 had optimum activity at pH 10, little to no affinity towards N-acetyl-gamma-aminobutyraldehyde (NAGABald) with a Km of approximately 10 mM and moderate affinity towards gamma-guanidinobutyraldehyde (GGBald) and betaine aldehyde (bet-ald) with Km values of approximately 260 mu M and 63 mu M respectively. A lower Km of approximately 9 mu M was observed with gamma-aminobutyraldehyde (GABald), suggesting BAD2 has a higher affinity towards this substate in vivo. The enzyme encoded on chromosome four, BAD1, had optimum activity at pH 9.5, showed little to no affinity towards bet-ald with a Km of 3 mM and had moderate affinity towards GGBald, NAGABald and GABald with Km values of approximately 545, 420 and 497 mu M respectively. BAD1 had a half life roughly double that of BAD2. We discuss the implications of these findings on the pathway of fragrance generation in Basmati and Jasmine rice and the potential of rice to accumulate the osmoprotectant glycine betaine.