Iwaki Masayo, Andrianambinintsoa Sandra, Rich Peter, Breton Jacques
SBE/DBCM, CEA-Saclay, Gif-sur-Yvette, France.
Spectrochim Acta A Mol Biomol Spectrosc. 2002 May;58(7):1523-33. doi: 10.1016/s1386-1425(02)00040-9.
Chemically induced Fourier transform infrared difference spectra associated with redox transitions of several primary electron donors and acceptors in photosynthetic reaction centers (RCs) have been compared with the light-induced FTIR difference spectra involving the same cofactors. The RCs are deposited on an attenuated total reflection (ATR) prism and form a film that is enclosed in a flow cell. Redox transitions in the film of RCs can be repetitively induced either by perfusion of buffers poised at different redox potentials or by illumination. The perfusion-induced ATR-FTIR difference spectra for the oxidation of the primary electron donor P in the RCs of the purple bacteria Rb. sphaeroides and Rp. viridis and P700 in the photosystem 1 of Synechocystis 6803, as well as the Q(A)/Q(A) transition of the quinone acceptor (Q(A)) in Rb. sphaeroides RCs are reported for the first time. They are compared with the light-induced ATR-FTIR difference spectra P+Q(A)/PQ(A) for the RCs of Rb. sphaeroides and P700+/P700 for photosystem 1. It is shown that the perfusion-induced and light-induced ATR-FTIR difference spectra recorded on the same RC film display identical signal to noise ratios when they are measured under comparable conditions. The ATR-FTIR difference spectra are very similar to the equivalent FTIR difference spectra previously recorded upon photochemical or electrochemical excitation of these RCs in the more conventional transmission mode. The ATR-FTIR technique requires a smaller amount of sample compared with transmission FTIR and allows precise control of the aqueous environment of the RC films.
已将与光合反应中心（RCs）中几种初级电子供体和受体的氧化还原转变相关的化学诱导傅里叶变换红外差谱，与涉及相同辅因子的光诱导傅里叶变换红外差谱进行了比较。反应中心沉积在衰减全反射（ATR）棱镜上，并形成封闭在流通池中的薄膜。通过灌注处于不同氧化还原电位的缓冲液或光照，可重复诱导反应中心薄膜中的氧化还原转变。首次报道了紫色细菌球形红杆菌（Rb. sphaeroides）和绿色红杆菌（Rp. viridis）的反应中心中初级电子供体P的氧化、集胞藻6803光系统1中P700的氧化以及球形红杆菌反应中心中醌受体（Q(A)）的Q(A)/Q(A)转变的灌注诱导ATR - FTIR差谱，并将它们与球形红杆菌反应中心的光诱导ATR - FTIR差谱P + Q(A)/PQ(A)以及光系统1的P700 +/P700进行了比较。结果表明，在可比条件下测量时，在同一反应中心薄膜上记录的灌注诱导和光诱导ATR - FTIR差谱显示出相同的信噪比。ATR - FTIR差谱与先前在更传统的透射模式下对这些反应中心进行光化学或电化学激发时记录的等效傅里叶变换红外差谱非常相似。与透射傅里叶变换红外相比，ATR - FTIR技术所需的样品量更少，并且能够精确控制反应中心薄膜的水环境。
