Changes in primary donor hydrogen-bonding interactions in mutant reaction centers from Rhodobacter sphaeroides: identification of the vibrational frequencies of all the conjugated carbonyl groups.
Changes in primary donor hydrogen-bonding interactions in mutant reaction centers from Rhodobacter sphaeroides: identification of the vibrational frequencies of all the conjugated carbonyl groups.
复制标题
DOI：
10.1021/bi00173a004
复制
发表时间：
1994-02
期刊：
影响因子：
2.9
通讯作者：
T. Mattioli;J. Williams;J. P. Allen;B. Robert
中科院分区：
文献类型：
--
作者：
T. Mattioli;J. Williams;J. P. Allen;B. Robert
利用近红外激发傅立叶变换（FT）拉曼光谱测定了在P附近发生突变的球形红杆菌反应中心中主要供体P的氢键态的具体变化。该技术使用1064 nm激发，选择性地提供了P在其还原态下的先前增强的振动谱，而不是其他反应中心发色团和蛋白质的贡献，并获得了有关P及其氢键相互作用的结构信息。所研究的突变如下：Leu M160—>His, Leu L131—>His， D9双突变体（Leu M160—>His + Leu L131—>His）， Phe M197—>His和His L168—>Phe。这些突变旨在引入新的或打破现有的P. C9和C2羰基的氢键。在先前分配的基础上[Mattioli， T. A., Hoffmann， A., Robert， B., Schrader， B., & Lutz， M. (1991) Biochemistry 30, 4648-4654]，这些突变体的FT拉曼光谱显示了P羰基与蛋白质的氢键相互作用的预测变化。本研究结果使我们能够明确地确定Rb中P的C2和C9羰基振子。sphaeroides。从P的其他物理化学性质，包括氧化还原电位和P+态的电子不对称性，讨论了遗传引入的氢键相互作用。本文讨论了蛋白质与P的共轭羰基氢键的变化并不是导致P/P+氧化还原中点电位发生大规模修饰的唯一因素，氢键供体的化学性质在这种修饰中起着重要作用。
Specific changes in the hydrogen-bonding states of the primary donor, P, in reaction centers from Rhodobacter sphaeroides bearing mutations near P were determined using near-infrared excited Fourier transform (FT) Raman spectroscopy. This technique, using 1064-nm excitation, provides the preresonantly enhanced vibrational spectrum of P in its reduced state selectively over the contributions of the other reaction center chromophores and protein and yields structural information concerning P and its hydrogen-bonding interactions. The mutations studied were as follows: Leu M160-->His, Leu L131-->His, the D9 double mutant (Leu M160-->His + Leu L131-->His), Phe M197-->His, and His L168-->Phe. These mutations were designed to introduce new, or to break existing, hydrogen bonds to the C9 and C2 carbonyl groups of P. On the basis of previous assignments [Mattioli, T. A., Hoffmann, A., Robert, B., Schrader, B., & Lutz, M. (1991) Biochemistry 30, 4648-4654], the FT Raman spectra of these mutants show the predicted changes in hydrogen bond interactions of P carbonyl groups with the protein. The results of this study have permitted us to unambiguously identify the C2 and C9 carbonyl vibrators of P in Rb. sphaeroides. The genetically introduced hydrogen bond interactions are discussed in terms of other physicochemical properties of P including the redox potential and electronic asymmetry in the P+ state. It is discussed that changes in protein hydrogen bonding to the conjugated carbonyl groups of P alone are not the sole factor that contributes to the sizeable modifications of the P/P+ redox midpoint potentials, and that the chemical nature of the hydrogen bond donor plays a significant role in this modification.