Oxygen-independent alkane formation by non-heme iron-dependent cyanobacterial aldehyde decarbonylase: investigation of kinetics and requirement for an external electron donor.
Oxygen-independent alkane formation by non-heme iron-dependent cyanobacterial aldehyde decarbonylase: investigation of kinetics and requirement for an external electron donor.
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DOI：
10.1021/bi2012417
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发表时间：
2011-12-13
期刊：
影响因子：
2.9
通讯作者：
Marsh, E. Neil G.
中科院分区：
文献类型：
--
作者：
Eser, Bekir E.;Das, Debasis;Han, Jaehong;Jones, Patrik R.;Marsh, E. Neil G.
蓝藻醛脱羰酶（cAD）在结构上是加氧酶的二铁羧酸盐家族的成员。我们先前报道了来自海洋原绿球藻的cAD催化醛的不寻常水解以在需要外部还原系统但不需要氧气的反应中产生烷烃和甲酸酯（Das等人，2011年，Angew。50，7148-7152）。在这里，我们证明了来自不同蓝藻类的cAD，包括来自N。据报道，puntiformes是氧依赖性的，在厌氧条件下以快得多的速率催化醛脱羰基，并且甲酸盐中的氧来自水。cAD的极低活性（< 1转化率/h）似乎是由测定中使用的铁氧还蛋白还原系统的抑制和底物的低溶解度引起的。用电子介质吩嗪硫酸甲酯取代铁氧还蛋白，使酶能够与各种化学还原剂一起发挥作用，其中NADH的活性最高。NADH在翻转过程中不会被消耗，这与还原系统在反应中的拟议催化作用一致雅阁。对于十八醛（产物形成的爆发阶段），观察到kprod = 3.4 ± 0.5 min−1，表明在测定条件下化学不是速率决定性的。对于可溶性更高的底物庚醛，kcat = 0.17 ± 0.01 min−1，没有观察到爆发相，表明化学步骤限制了该底物的反应。
Cyanobacterial aldehyde decarbonylase (cAD) is, structurally, a member of the di-iron carboxylate family of oxygenases. We previously reported that cAD from Prochlorococcus marinus catalyzes the unusual hydrolysis of aldehydes to produce alkanes and formate in a reaction that requires an external reducing system but does not require oxygen (Das et al., 2011, Angew. Chem. 50, 7148–7152). Here we demonstrate that cADs from divergent cyanobacterial classes, including the enzyme from N. puntiformes that was reported to be oxygen dependent, catalyze aldehyde decarbonylation at a much faster rate under anaerobic conditions, and that the oxygen in formate derives from water. The very low activity (< 1 turn-over/h) of cAD appears to result from inhibition by the ferredoxin reducing system used in the assay and the low solubility of the substrate. Replacing ferredoxin with the electron mediator phenazine methosulfate allowed the enzyme to function with various chemical reductants, with NADH giving the highest activity. NADH is not consumed during turn-over, in accord with the proposed catalytic role for the reducing system in the reaction. With octadecanal, a burst phase of product formation, kprod = 3.4 ± 0.5 min−1 is observed indicating that chemistry is not rate-determining under the conditions of the assay. With the more soluble substrate, heptanal, kcat = 0.17 ± 0.01 min−1 and no burst phase is observed, suggesting that a chemical step is limiting in the reaction of this substrate.
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影响因子：
3.9
作者：
Schneider-Belhaddad, F;Kolattukudy, P
通讯作者：
Kolattukudy, P
影响因子：
3.8
作者：
YODER, JA;DENLINGER, DL;KOLATTUKUDY, PE
通讯作者：
KOLATTUKUDY, PE
影响因子：
5.1
作者：
Cahoon, EB;Coughlan, SJ;Shanklin, J
通讯作者：
Shanklin, J
影响因子：
15
作者：
Warui, Douglas M.;Li, Ning;Norgaard, Hanne;Krebs, Carsten;Bollinger, J. Martin, Jr.;Booker, Squire J.
通讯作者：
Booker, Squire J.
影响因子：
11.6
作者：
Aarts, MGM;Keijzer, CJ;Pereira, A
通讯作者：
Pereira, A