Peloquin J M, Bylina E J, Youvan D C, Bocian D F
Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213.
Biochemistry. 1990 Sep 11;29(36):8417-24. doi: 10.1021/bi00488a031.
Resonance Raman (RR) spectra are reported for the photosynthetic reaction center (RC) proteins from Rhodobacter capsulatus wild type and the genetically modified systems GluL104----Leu and HisM200----Leu. The spectra were obtained with a variety of excitation wavelengths, spanning the UV, violet, and yellow-green regions of the absorption spectrum, and at temperatures of 30 and 200 K. The RR data indicate that the structures of the bacteriochlorin pigments in RCs from Rb. capsulatus wild type are similar to those in RCs from Rhodobacter sphaeroides wild type. The data also show that the amino acid modifications near the primary electron acceptor (GluL104----Leu) and special pair (HisM200----Leu) perturb only those bacteriochlorin pigments near the site of the mutation and do not influence the structures of the other pigments in the RC. In the case of the GluL104----Leu mutant, elimination of the hydrogen bond to the C9 keto group of BPhL results in frequency shifts of RR bands of certain skeletal modes of the macrocycle. This allows the assignment of bands to the individual BPhL and BPhM pigments. In the case of the HisM200----Leu mutant, in which the special pair is comprised of a bacteriochlorophyll (BChl)-bacteriopheophytin (BPh) heterodimer rather than the BChl2 unit bound in the wild type, certain skeletal vibrations due to the additional BPh unit are identified. The frequencies of these modes are similar to those of the analogous vibrations BPhL and BPhM, which indicates that the structure of the BPh in the heterodimer is not unusual in any discernible way.(ABSTRACT TRUNCATED AT 250 WORDS)
报道了来自荚膜红细菌野生型以及基因改造系统GluL104→Leu和HisM200→Leu的光合反应中心（RC）蛋白的共振拉曼（RR）光谱。这些光谱是在多种激发波长下获得的，涵盖吸收光谱的紫外、紫光和黄绿区域，温度分别为30K和200K。RR数据表明，荚膜红细菌野生型RC中细菌叶绿素色素的结构与球形红细菌野生型RC中的相似。数据还显示，初级电子受体附近（GluL104→Leu）和特殊对附近（HisM200→Leu）的氨基酸修饰仅扰乱突变位点附近的那些细菌叶绿素色素，而不影响RC中其他色素的结构。对于GluL104→Leu突变体，消除与BPhL的C9酮基的氢键会导致大环某些骨架模式的RR带发生频率偏移。这使得能够将谱带分配给各个BPhL和BPhM色素。对于HisM200→Leu突变体（其中特殊对由细菌叶绿素（BChl）-细菌脱镁叶绿素（BPh）异二聚体组成，而不是野生型中结合的BChl2单元），鉴定出了由于额外的BPh单元引起的某些骨架振动。这些模式的频率与类似振动BPhL和BPhM的频率相似，这表明异二聚体中BPh的结构在任何可辨别的方面都没有异常。（摘要截短于250字）
