Roberts C M, Conrad R S, Sokatch J R
Arch Microbiol. 1978 Apr 27;117(1):99-108. doi: 10.1007/BF00689358.
The purpose of the present study was to determine if the enoyl coenzyme A hydratase formed by Pseudomonas putida during growth on isoleucine was a unique enzyme specific for isoleucine metabolism. The highest levels of the hydratase were formed during growth on isoleucine intermediates and the lowest levels during growth on glutamate and glucose. Data from growth experiments revealed that 2-methyl-3-hydroxybutyryl coenzyme A hydratase, an enzyme unique to isoleucine metabolism and enoyl coenzyme A hydratase were coordinately induced, but that 3-hydroxyacyl coenzyme A dehydrogenase was under separate control. The hydratase was purified 180-fold from isoleucine cells, and its physical and catalytic properties reported. The highest activity was with crotonyl coenzyme A,Vmax = 1100 x 10(3) moles/min mole enzyme, next was tiglyl coenzyme A, Vmax = 61 x 10(3) moles/min mole enzyme, and last was 3-methyl-crotonyl coenzyme A, Vmax = 2.3 x 10(3) moles/min mole enzyme. Enzyme purified from butyrate cells had the same elution patterns during column chromatography and catalytic properties as the enzyme from isoleucine cells. These data support the conclusion that a single enzyme in P. putida is responsible for the hydration of both tiglyl coenzyme A and crotonyl coenzyme A.
本研究的目的是确定恶臭假单胞菌在以异亮氨酸为碳源生长过程中形成的烯酰辅酶A水合酶是否是一种对异亮氨酸代谢具有特异性的独特酶。水合酶的最高水平是在以异亮氨酸中间产物为碳源生长时形成的，而在以谷氨酸和葡萄糖为碳源生长时水平最低。生长实验数据表明，2-甲基-3-羟基丁酰辅酶A水合酶（一种异亮氨酸代谢特有的酶）和烯酰辅酶A水合酶是协同诱导的，但3-羟基酰基辅酶A脱氢酶受不同的调控。从以异亮氨酸为碳源生长的细胞中纯化出水合酶180倍，并报道了其物理和催化特性。最高活性是对巴豆酰辅酶A而言，Vmax = 1100×10³ 摩尔/分钟·摩尔酶，其次是惕各酰辅酶A，Vmax = 61×10³ 摩尔/分钟·摩尔酶，最后是3-甲基巴豆酰辅酶A，Vmax = 2.3×10³ 摩尔/分钟·摩尔酶。从以丁酸盐为碳源生长的细胞中纯化的酶在柱色谱中的洗脱模式和催化特性与从以异亮氨酸为碳源生长的细胞中得到的酶相同。这些数据支持这样的结论，即恶臭假单胞菌中的一种单一酶负责惕各酰辅酶A和巴豆酰辅酶A的水合作用。
