The laser-induced blue state of bacteriorhodopsin: mechanistic and color regulatory roles of protein-protein interactions, protein-lipid interactions, and metal ions.
The laser-induced blue state of bacteriorhodopsin: mechanistic and color regulatory roles of protein-protein interactions, protein-lipid interactions, and metal ions.
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激光诱导的细菌视紫红质的蓝色状态：蛋白质-蛋白质相互作用、蛋白质-脂质相互作用和金属离子的机械和颜色调节作用。
DOI：
10.1021/ja010116a
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发表时间：
2002
影响因子：
15
通讯作者：
Kofron,JohnT
中科院分区：
文献类型：
--
作者：
Masthay,MarkB;Sammeth,DavidM;Helvenston,MerrittC;Buckman,CharlesB;Li,Wuyi;Cde-Baca,MichaelJ;Kofron,JohnT
在本文中，我们表征的机制作用的结晶紫膜（PM）的晶格，最早的细菌视紫红质（BR）的光循环中间体，和二价阳离子在PM转换为激光诱导的蓝膜（LIBM; λmax= 605 nm）在强烈的532 nm脉冲照射后，通过比较的光转换PM与单体BR溶解在还原Triton X-100去污剂。单体BR形成了一个以前未被发现的无色单体光产物，它在可见光区缺乏发色团带，但在360 nm附近出现了一个新的带，类似于LIBM中的360 nm带。LIBM和无色单体中的360 nm带源自席夫碱还原的视黄基发色团，其保持与细菌视蛋白共价连接。PM→LIBM和单体→无色单体的光转化都是由类似的双光子机制介导的，这表明光化学作用局限于单个BR单体内，不受BR-BR相互作用的影响。这些光转换的极大双光子吸收系数（≥ 106 cm ~ 4·s molecule ~（-1）photon ~（-1））、产生高产量LIBM的脉冲的时间和光谱特性以及PM→LIBM光转换的作用光谱都表明PM→LIBM和Mon→CMon光转换都是由顺序双光子机制介导的， 是吸收第二个光子的中间体。紫色→蓝色的颜色变化是由于PM晶格随后的构象扰动导致PM表面的Ca 2+和Mg 2+离子被去除。
In this paper we characterize the mechanistic roles of the crystalline purple membrane (PM) lattice, the earliest bacteriorhodopsin (BR) photocycle intermediates, and divalent cations in the conversion of PM to laser-induced blue membrane (LIBM; λmax= 605 nm) upon irradiation with intense 532 nm pulses by contrasting the photoconversion of PM with that of monomeric BR solubilized in reduced Triton X-100 detergent. Monomeric BR forms a previously unreportedcolorless monomerphotoproduct which lacks a chromophore band in the visible region but manifests a new band centered near 360 nm similar to the 360 nm band in LIBM. The 360 nm band in both LIBM and colorless monomer originates from a Schiff base-reduced retinyl chromophore which remains covalently linked to bacterioopsin. Both the PM→LIBM and monomer→colorless monomer photoconversions are mediated by similar biphotonic mechanisms, indicating that the photochemistry is localized within single BR monomers and is not influenced by BR−BR interactions. The excessively large two-photon absorptivities (≥106cm4s molecule-1photon-1) of these photoconversions, the temporal and spectral characteristics of pulses which generate LIBM in high yield, and an action spectrum for the PM→LIBM photoconversion all indicate that the PM→LIBM and Mon→CMon photoconversions are both mediated by a sequential biphotonic mechanism in which is the intermediate which absorbs the second photon. The purple→blue color change results from subsequent conformational perturbations of the PM lattice which induce the removal of Ca2+and Mg2+ions from the PM surface.