Aurich H, Sorger H, Bergmann R, Lasch J
Biol Chem Hoppe Seyler. 1987 Feb;368(2):101-9.
In recent investigations we were able to demonstrate that the NADP-dependent aldehyde dehydrogenase of Acinetobacter calcoaceticus is an inducible enzyme localized in intracytoplasmic membranes limiting alkane inclusions. Long-chain aliphatic hydrocarbons and alkanols are inducers of the enzyme. It was purified by us and now kinetically characterized using the enzyme-micelle form, which contains bacterial phospholipids and a detergent (sodium cholate), too. The pH optimum of aldehyde dehydrogenase was determined to be at pH 10. The enzyme showed substrate inhibition (by aldehyde excess). The Ks and Km values of the leading substrate NADP+ were found to be 8.6 X 10(-5) and 10.3 X 10(-5)M independent of the chain-length of the aldehydes. The Km values of the aldehydes decreased depending on increasing chain-length (butanal: 1.6 X 10(-3), decanal: 1.5 X 10(-6)M). The Ki values (for inhibition by aldehyde excess) showed a similar behaviour (butanal: 7.5 X 10(-3), decanal: 3.5 X 10(-5)M) as well as the optimal aldehyde concentrations inducing the "maximal" reaction velocity (butanal: 5mM, decanal: 6 microM). The number of inhibiting aldehyde molecules per enzyme-substrate complex was determined to be n = 1. NADPH showed product inhibition kinetics (Ki(NADPH) = 2.2 X 10(-4)M), fatty acids did not. We were unable to measure a reverse reaction. The following ions and organic compounds were non-competitive inhibitors of the enzyme: Sn2+, Fe2+, Cu2+, BO3(3-), CN-, EDTA, o-phenanthroline, p-chloromercuri-benzoate, mercaptoethanol, phenylmethylsulfonyl fluoride, and diisopropylfluorophosphate; iodoacetate did not influence enzyme activity. Chloral hydrate was a competitive inhibitor of the aldehydes. Ethyl butyrate activates the enzyme, dependent on the chain-length of the aldehyde substrates.
在最近的研究中，我们能够证明醋酸钙不动杆菌的NADP依赖性醛脱氢酶是一种诱导酶，定位于限制烷烃包涵体的胞内膜中。长链脂肪烃和链烷醇是该酶的诱导剂。我们对其进行了纯化，现在使用含有细菌磷脂和去污剂（胆酸钠）的酶-胶束形式对其进行了动力学表征。醛脱氢酶的最适pH值确定为10。该酶表现出底物抑制（因醛过量）。主要底物NADP+的Ks和Km值分别为8.6×10⁻⁵和10.3×10⁻⁵M，与醛的链长无关。醛的Km值随链长增加而降低（丁醛：1.6×10⁻³，癸醛：1.5×10⁻⁶M）。Ki值（因醛过量而抑制）表现出类似的行为（丁醛：7.5×10⁻³，癸醛：3.5×10⁻⁵M），以及诱导“最大”反应速度的最佳醛浓度（丁醛：5mM，癸醛：6μM）。每个酶-底物复合物中抑制性醛分子的数量确定为n = 1。NADPH表现出产物抑制动力学（Ki(NADPH)=2.2×10⁻⁴M），脂肪酸则没有。我们无法测量逆向反应。以下离子和有机化合物是该酶的非竞争性抑制剂：Sn²⁺、Fe²⁺、Cu²⁺、BO₃³⁻、CN⁻、EDTA、邻菲罗啉、对氯汞苯甲酸、巯基乙醇、苯甲基磺酰氟和二异丙基氟磷酸酯；碘乙酸不影响酶活性。水合氯醛是醛的竞争性抑制剂。丁酸乙酯激活该酶，这取决于醛底物的链长。
