de Paula J C, Liefshitz A, Hinsley S, Lin W, Chopra V, Long K, Williams S A, Belts S, Yocum C F
Department of Chemistry, Haverford College, Pennsylvania 19041.
Biochemistry. 1994 Feb 15;33(6):1455-66. doi: 10.1021/bi00172a023.
We report the fluorescence decay kinetics and the vibrational properties of chlorophyll a bound to the 47-kDa antenna protein (CP47) of spinach photosystem II. The chlorophyll fluorescence of CP47 samples decays with four lifetimes (tau = 75.8 ps, 1.05 ns, 3.22 ns, and 5.41 ns). The 75.8-ps and 3.22-ns components are associated with chlorophyll a bound to relatively intact centers, the 1.05-ns component corresponds to chlorophyll bound to centers that are slightly perturbed, and the the 5.41-ns phase probably originates from centers that are severely denatured. The resonance Raman spectrum of CP47 at 441.6 nm (this work) and at 406.7 nm [de Paula, J. C., Ghanotakis, D. F., Bowlby, N. R., Dekker, J. P., Yocum, C. F., & Babcock, G. T. (1990) in Current Research in Photosynthesis (Baltscheffsky, M., Ed.), Vol. I, pp 643-646, Kluwer Academic Publishers, Dordrecht, The Netherlands] shows heterogeneity in the C = O stretching region. This part of the spectrum monitors the environment of the keto group at position 9 of the chlorophyll a molecule. We show that several structurally distinct pools of chlorophyll a are bound to CP47. Four of these may be distinguished by their C9 = O stretching frequencies (nu C = O = 1670, 1688, 1693, and 1701 cm-1). By analyzing the resonance enhancement pattern of these modes, we ascribe the 1693-cm-1 vibration to denatured centers. Of the remaining populations, we propose that the 1670-cm-1 vibration is consistent with a hydrogen bond between the C9 = O group of chlorophyll a and the protein. We elaborate on the role of this chromophore-protein interaction in the mechanism of energy transfer within the 47-kDa antenna protein.
我们报告了与菠菜光系统II的47 kDa天线蛋白（CP47）结合的叶绿素a的荧光衰减动力学和振动特性。CP47样品的叶绿素荧光以四个寿命（τ = 75.8 ps、1.05 ns、3.22 ns和5.41 ns）衰减。75.8 ps和3.22 ns的成分与结合在相对完整中心的叶绿素a相关，1.05 ns的成分对应于结合在略有扰动中心的叶绿素，而5.41 ns的相可能起源于严重变性的中心。CP47在441.6 nm（本研究）和406.7 nm [德保拉，J.C.，加诺塔基斯，D.F.，鲍尔比，N.R.，德克尔，J.P.，约库姆，C.F.，&巴布科克，G.T.（1990年），《光合作用的当前研究》（巴尔切夫斯基，M.编），第一卷，第643 - 646页，克鲁维尔学术出版社，荷兰多德雷赫特]处的共振拉曼光谱显示在C = O伸缩区域存在异质性。光谱的这一部分监测叶绿素a分子第9位酮基的环境。我们表明，几种结构不同的叶绿素a池与CP47结合。其中四个可以通过它们的C9 = O伸缩频率（νC = O = 1670、1688、1693和1701 cm⁻¹）来区分。通过分析这些模式的共振增强模式，我们将1693 cm⁻¹的振动归因于变性中心。在其余的群体中，我们提出1670 cm⁻¹的振动与叶绿素a的C9 = O基团和蛋白质之间的氢键一致。我们详细阐述了这种发色团 - 蛋白质相互作用在47 kDa天线蛋白内能量转移机制中的作用。
