Protein modifications affecting triplet energy transfer in bacterial photosynthetic reaction centers.
Protein modifications affecting triplet energy transfer in bacterial photosynthetic reaction centers.
复制标题
影响细菌光合反应中心三重态能量转移的蛋白质修饰。
DOI：
10.1016/s0006-3495(98)77968-8
复制
发表时间：
1998
影响因子：
3.4
通讯作者：
Frank,HA
中科院分区：
文献类型：
--
作者：
Laible,PD;Chynwat,V;Thurnauer,MC;Schiffer,M;Hanson,DK;Frank,HA
研究了一个大家族突变株光合反应中心（RC）中特殊对（P）到类胡萝卜素（C）的三重态能量转移效率。突变体携带的位置L181和/或M208附近的叶绿素为基础的辅因子的复合物的非活性和活性侧，分别取代。在10 K的光调制电子顺磁共振，其中三重态能量转移是热禁止的，揭示了突变不扰动P的电子分布。在温度≥ 70 K，我们观察到减少的信号从类胡萝卜素在大多数RC与L181取代。特别是，三重态转移效率降低，在所有的RC中，赖氨酸在L181捐赠的第六个配体的单体细菌叶绿素BB。用几个极性残基替换复合物活性侧M208处的天然Tyr增加了转移效率。RC中转移效率的差异表明蛋白质环境影响发色团的电子重叠的能力，从而影响三重态能量转移的热屏障。
The efficiency of triplet energy transfer from the special pair (P) to the carotenoid (C) in photosynthetic reaction centers (RCs) from a large family of mutant strains has been investigated. The mutants carry substitutions at positions L181 and/or M208 near chlorophyll-based cofactors on the inactive and active sides of the complex, respectively. Light-modulated electron paramagnetic resonance at 10K, where triplet energy transfer is thermally prohibited, reveals that the mutations do not perturb the electronic distribution of P. At temperatures≥70K, we observe reduced signals from the carotenoid in most of the RCs with L181 substitutions. In particular, triplet transfer efficiency is reduced in all RCs in which a lysine at L181 donates a sixth ligand to the monomeric bacteriochlorophyll BB. Replacement of the native Tyr at M208 on the active side of the complex with several polar residues increased transfer efficiency. The difference in the efficiencies of transfer in the RCs demonstrates the ability of the protein environment to influence the electronic overlap of the chromophores and thus the thermal barrier for triplet energy transfer.