Kinetic analysis of mouse retinal dehydrogenase type-2 (RALDH2) for retinal substrates
Kinetic analysis of mouse retinal dehydrogenase type-2 (RALDH2) for retinal substrates
复制标题
DOI：
10.1016/s0167-4838(02)00213-3
复制
发表时间：
2002-04-01
期刊：
影响因子：
--
通讯作者：
Bhat, PV
中科院分区：
文献类型：
--
作者：
Gagnon, I;Duester, G;Bhat, PV
视网膜脱氢酶（RALDH）同工酶催化视黄醇最终氧化成视黄酸（RA），这是胚胎发生和组织分化所必需的。为了了解小鼠2型RALDH在合成结合和激活核RA受体所需的配体（全反式和9-顺式RA）中的作用，我们确定了RALDH 2对各种视网膜底物的详细动力学性质。纯化的重组RALDH 2显示了全反式视黄醇氧化的最佳pH值为9.0。与25 ℃相比，37 ℃下酶的活性较低。全反式视黄醛转化为RA的效率分别是13-顺式和9-反式视黄醛的2倍和5倍。全反式和13-顺式视黄醛的K值相似（分别为0.66和0.62 μ M）。然而，RALDH 2对9-顺式视网膜底物的Km（2.25 μ M）是全反式和13-顺式视网膜底物的3倍。在测试其抑制或激活RALDH 2的能力的几种试剂中，柠檬醛和对羟基汞苯甲酸（p-HMB）抑制反应，MgCl 2激活反应。RALDH 2的视网膜底物的动力学特性和对各种试剂的活性与先前报道的大鼠肾RALDH 1和人肝醛脱氢酶-1的比较显示出明显的差异。由于RALDH 2对全反式维甲酸具有较低的Km值和较高的催化效率，因此它可能参与体内全反式维甲酸的产生。(C)2002 Elsevier Science B. V.保留所有权利。
Retinal dehydrogenase (RALDH) isozymes catalyze the terminal oxidation of retinol into retinoic acid (RA) that is essential for embryogenesis and tissue differentiation. To understand the role of mouse type 2 RALDH in synthesizing the ligands (all-trans and 9-cis RA) needed to bind and activate nuclear RA receptors, we determined the detailed kinetic properties of RALDH2 for various retinal substrates. Purified recombinant RALDH2 showed a pH optimum of 9.0 for all-trans retinal oxidation. The activity of the enzyme was lower at 37degreesC compared to 25degreesC. The efficiency of conversion of all-trans retinal to RA was 2- and 5-fold higher than 13-cis and 9-eis retinal, respectively. The K for all-trans and 13-cis retinal were similar (0.66 and 0.62 muM, respectively). However, the K-m of RALDH2 for 9-cis retinal substrate (2.25 muM) was 3-fold higher compared to all-trans and 13-cis retinal substrates. Among several reagents tested for their ability to either inhibit or activate RALDH2, citral and para-hydroxymercuribenzoic acid (p-HMB) inhibited and MgCl2 activated the reaction. Comparison of the kinetic properties of RALDH2 for retinal substrates and its activity towards various reagents with those of previously reported rat kidney RALDH1 and human liver aldehyde dehydrogenase-1 showed distinct differences. Since RALDH2 has low K-m and high catalytic efficiency for all-trans retinal, it may likely be involved in the production of all-trans RA in vivo. (C) 2002 Elsevier Science B.V. All rights reserved.