Detection of formate, rather than carbon monoxide, as the stoichiometric coproduct in conversion of fatty aldehydes to alkanes by a cyanobacterial aldehyde decarbonylase.
Detection of formate, rather than carbon monoxide, as the stoichiometric coproduct in conversion of fatty aldehydes to alkanes by a cyanobacterial aldehyde decarbonylase.
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DOI：
10.1021/ja111607x
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发表时间：
2011-03-16
影响因子：
15
通讯作者：
Booker, Squire J.
中科院分区：
文献类型：
--
作者：
Warui, Douglas M.;Li, Ning;Norgaard, Hanne;Krebs, Carsten;Bollinger, J. Martin, Jr.;Booker, Squire J.
在最近发现的途径中的两个反应中的第二个，通过该途径在蓝藻中将饱和脂肪酸转化为烷烃（和将不饱和脂肪酸转化为烯烃），需要通过酶醛脱羰基酶（AD）切断脂肪醛中间体的C1-C2键，所述酶醛脱羰基酶（AD）是具有未知组成的双核金属辅因子的铁蛋白样蛋白。我们测试了一氧化碳（CO），未能检测到烷烃合成的C1衍生副产物，十八醛（R-CHO，其中R = n-C17 H35）体外转化为十七烷（R-H）后，分离出的念珠藻AD在大肠杆菌中过量生产。相反，我们确定甲酸盐（HCO 2 −）是反应的化学计量副产物。同位素示踪实验的结果表明，醛氢保留在HCO 2 −中，而烷烃的新生甲基中的氢至少部分来自溶剂。有了这些特点，反应似乎是正式水解，但不可能的水解机制具有初级负碳离子作为离去基团，结构相似性的AD的其他O2激活非血红素二铁蛋白，并依赖于在体外AD活性的存在下的还原系统牵连某种类型的氧化还原机制。两个可能的解决方案，这个难题的建议。
The second of two reactions in a recently discovered pathway through which saturated fatty acids are converted to alkanes (and unsaturated fatty acids to alkenes) in cyanobacteria entails scission of the C1–C2 bond of a fatty aldehyde intermediate by the enzyme aldehyde decarbonylase (AD), a ferritin-like protein with a dinuclear metal cofactor of unknown composition. We tested for and failed to detect carbon monoxide (CO), the proposed C1-derived co-product of alkane synthesis, following the in vitro conversion of octadecanal (R-CHO, where R = n-C17H35) to heptadecane (R-H) by the Nostoc punctiforme AD isolated following its overproduction in Escherichia coli. Instead, we identified formate (HCO2−) as the stoichiometric co-product of the reaction. Results of isotope-tracer experiments indicate that the aldehyde hydrogen is retained in the HCO2− and the hydrogen in the nascent methyl group of the alkane originates, at least in part, from solvent. With these characteristics, the reaction appears to be formally hydrolytic, but the improbability of a hydrolytic mechanism having the primary carbanion as the leaving group, the structural similarity of the ADs to other O2-activating non-heme di-iron proteins, and the dependence of in vitro AD activity on the presence of a reducing system implicate some type of redox mechanism. Two possible resolutions to this conundrum are suggested.
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影响因子：
15
作者：
Korboukh, Victoria Korneeva;Li, Ning;Barr, Eric W.;Bollinger, J. Martin, Jr.;Krebs, Carsten
通讯作者：
Krebs, Carsten
影响因子：
2.9
作者：
Jiang, Wei;Hoffart, Lee M.;Martin Bollinger, J., Jr.
通讯作者：
Martin Bollinger, J., Jr.
影响因子：
56.9
作者：
Jiang, Wei;Yun, Danny;Bollinger, J. Martin, Jr.
通讯作者：
Bollinger, J. Martin, Jr.
DOI：
10.1016/0005-2795(74)90161-5
发表时间：
1974-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
IIZUKA, T;YAMAMOTO, H;YONETANI, T
通讯作者：
YONETANI, T
影响因子：
3.8
作者：
YODER, JA;DENLINGER, DL;KOLATTUKUDY, PE
通讯作者：
KOLATTUKUDY, PE