The primary electron acceptor of green sulfur bacteria, bacteriochlorophyll 663, is chlorophyll α esterified with Δ2,6-phytadienol
The primary electron acceptor of green sulfur bacteria, bacteriochlorophyll 663, is chlorophyll α esterified with Δ2,6-phytadienol
复制标题
DOI：
10.1023/a:1006480629059
复制
发表时间：
2000-01-01
影响因子：
3.7
通讯作者：
Kano, H
中科院分区：
文献类型：
--
作者：
Kobayashi, M;Oh-oka, H;Kano, H
采用改进的提纯工艺，从一个粗制的反应中心复合体中高纯度地分离得到绿色硫磺细菌的初级电子受体细菌叶绿素(BCHL)663，并通过快原子轰击质谱学(FAB-MASS)、H-1-和C-13-核磁共振谱、双量子过滤相关谱(DQF-COSY)、异核多量子相干(HMQC)和异核多键相关(HMBC)光谱测定了其分子结构。Bchl 663比植物Chla小2.0个质量单位。核磁共振谱表明，BChl 663的大环与Chla相同。在酯化醇中，BChl 663的单态P3(1)信号的高场侧观察到单态P7(1)信号，而在Chla中P7(1)的双峰与P11(1)峰重叠。在Chla中没有P7-质子信号，而P6-质子在BChl 663的三线P2-质子信号附近以三线信号出现。这些结果表明，在BCHL663中，除了P2和P3之间的C=C双键外，P6和P7之间还存在C=C双键。因此，BCHL 663的结构是用2，6-植二烯酚而不是植醇酯化的。除了BCHL 663外，每个反应中心还存在BCHL a的13(2)-同分异构体BCHL a‘的两个分子，这可能是主要的电子供体。
The primary electron acceptor of green sulfur bacteria, bacteriochlorophyll (BChl) 663, was isolated at high purity by an improved purification procedure from a crude reaction center complex, and the molecular structure was determined by fast atom bombardment mass spectroscopy (FAB-mass), H-1- and C-13-NMR spectrometry, double quantum filtered correlation spectroscopy (DQF-COSY), heteronuclear multiple-quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC) spectral measurements. BChl 663 was 2.0 mass units smaller than plant Chl a. The NMR spectra showed that the macrocycle was identical to that of Chl a. In the esterifying alcohol, a singlet P7(1) signal was observed at the high-field side of the singlet P3(1) signal in BChl 663, while a doublet peak of P7(1) overlapped that of P11(1) in Chl a. A signal of P7-proton, seen in Chl a, was lacking, and the P6-proton appeared as a triplet signal near the triplet P2-proton signal in BChl 663. These results indicate the presence in BChl 663 of a C=C double bond between P6 and P7 in addition to that between P2 and P3. The structure of BChl 663 was hence concluded to be Chl a esterified with 2,6-phytadienol instead of phytol. In addition to BChl 663, two molecules of the 13(2)-epimer of BChl a, BChl a', were found to be present per reaction center, which may constitute the primary electron donor.