Perrino L A, Pierce S K
Department of Biology, University of Maryland, College Park, Maryland 20742, USA.
J Exp Zool. 2000 Feb 15;286(3):238-49.
Betaine aldehyde dehydrogenase (BADH), the terminal enzyme of the glycine betaine synthetic pathway was purified 245-fold from the mitochondria of Atlantic and Chesapeake Bay oyster populations acclimated to 350 mosm, using ammonium sulfate precipitation, anion exchange, and affinity chromatography. BADH from both populations functions at its maximum rate at 50-55 degrees C over a broad pH range (7.5-9). BADH activity is also modulated by increased [Na(+)] and [K(+)]. Although BADH from both populations has a similar V(max), BADH from Bay oysters has a substantially lower affinity for its substrate, betaine aldehyde, (K(m) = 0.36 mM), than BADH from Atlantic oysters (K(m) = 0.1 mM). Despite kinetic differences, BADH from both Atlantic and Chesapeake Bay oysters have the same molecular weight based on electrophoretic analysis. These differences in BADH enzyme kinetics between the two oyster populations probably partially explain the lower glycine betaine synthesis rates and concentrations in Chesapeake Bay oysters. J. Exp. Zool. 286:238-249, 2000.
甜菜碱醛脱氢酶（BADH）是甘氨酸甜菜碱合成途径的末端酶，利用硫酸铵沉淀、阴离子交换和亲和层析从适应350毫渗量浓度的大西洋牡蛎和切萨皮克湾牡蛎种群的线粒体中纯化了245倍。两个种群的BADH在50 - 55摄氏度、较宽的pH范围（7.5 - 9）内以最大速率发挥作用。BADH活性也受到[Na⁺]和[K⁺]增加的调节。尽管两个种群的BADH具有相似的Vmax，但切萨皮克湾牡蛎的BADH对其底物甜菜碱醛的亲和力（Km = 0.36 mM）明显低于大西洋牡蛎的BADH（Km = 0.1 mM）。尽管存在动力学差异，但基于电泳分析，大西洋牡蛎和切萨皮克湾牡蛎的BADH具有相同分子量。两个牡蛎种群之间BADH酶动力学的这些差异可能部分解释了切萨皮克湾牡蛎中较低的甘氨酸甜菜碱合成速率和浓度。《实验动物学杂志》286:238 - 249，2000年。
