Buckel W
Laboratorium für Mikrobiologie, Philipps-Universität, Marburg, Germany.
FEBS Lett. 1996 Jun 24;389(1):20-4. doi: 10.1016/0014-5793(96)00530-3.
Dehydratases have been detected in anaerobic bacteria which use 2-, 4- or 5-hydroxyacyl-CoA as substrates and are involved in the removal of hydrogen atoms from the unactivated beta- or gamma-positions. In addition there are bacterial dehydratases acting on 1,2-diols which are substrates lacking any activating group. These enzymes contain either FAD, or flavins + iron-sulfur clusters or coenzyme B12. It has been proposed that the overall dehydrations are actually reductions followed by oxidations or vice versa mediated by these prosthetic groups. Whereas the gamma-hydrogen of 5-hydroxyvaleryl-CoA is activated by a transient two-election alpha, beta-oxidation, the other substrates are proposed to require either a transient one-electron reduction or an oxidation to a ketyl (radical anion).
已在厌氧细菌中检测到脱水酶，这些细菌利用2-、4-或5-羟基酰基辅酶A作为底物，并参与从未活化的β-或γ-位去除氢原子。此外，还有作用于1,2-二醇的细菌脱水酶，1,2-二醇是缺乏任何活化基团的底物。这些酶要么含有黄素腺嘌呤二核苷酸（FAD），要么含有黄素+铁硫簇，要么含有辅酶B12。有人提出，整体脱水实际上是由这些辅基介导的还原反应后再进行氧化反应，反之亦然。虽然5-羟基戊酰辅酶A的γ-氢通过瞬时双电子α,β-氧化被激活，但其他底物则被认为需要瞬时单电子还原或氧化成酮基（自由基阴离子）。
