Anomalous Temperature Dependence of the Triplet-Triplet Energy Transfer in Cereibacter sphaeroides I(L177)H Mutant Reaction Centers

IF 2.3 4区 生物学 Q3 BIOCHEMISTRY & MOLECULAR BIOLOGY
Tatiana Yu. Fufina, Lyudmila G. Vasilieva, Irina B. Klenina, Ivan I. Proskuryakov
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引用次数: 0

Abstract

In photosynthetic reaction centers, quenching of the primary donor triplet state by energy transfer to the carotenoid molecule provides efficient suppression of generation of singlet-excited oxygen, potent chemical oxidant. This process in the Cereibacter sphaeroides reaction centers is thermoactivated, and discontinues at temperatures below 40 K. In these reaction centers, substitution of amino acid residue isoleucine at the 177 position of the L-subunit with histidine results in the sharp decrease of activation energy, so that the carotenoid triplets are populated even at 10 K. Activation energy of the T-T energy transfer was estimated as 7.5 cm–1, which is more than 10-fold lower than activation energy in the wild type reaction centers. At certain temperatures, the energy transfer in the mutant is decelerated, which is related to the increase of effective distance of the triplet-triplet transfer. To the best of our knowledge, the described mutation presents the first reaction center modification leading to the significant decrease in activation energy of the T-T energy transfer to carotenoid molecule. The I(L177)H mutant reaction centers present a considerable interest for further studies of the triplet state quenching mechanisms, and of other photophysical and photochemical processes in the reaction centers of bacterial photosynthesis.

Cereibacter sphaeroides I(L177)H 突变反应中心的三重三重能量转移的异常温度依赖性
在光合作用反应中心,通过向类胡萝卜素分子转移能量来淬灭初级供体三重态,从而有效地抑制了单激发氧这种强化学氧化剂的生成。据估计,T-T 能量转移的活化能为 7.5 cm-1,比野生型反应中心的活化能低 10 倍以上。在一定温度下,突变体中的能量转移速度减慢,这与三重-三重转移的有效距离增加有关。据我们所知,所述突变是导致类胡萝卜素分子 T-T 能量转移活化能显著降低的第一个反应中心修饰。I(L177)H 突变体反应中心对进一步研究三重态淬灭机制以及细菌光合作用反应中心的其他光物理和光化学过程具有重大意义。
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来源期刊
Biochemistry (Moscow)
Biochemistry (Moscow) 生物-生化与分子生物学
CiteScore
4.70
自引率
3.60%
发文量
139
审稿时长
2 months
期刊介绍: Biochemistry (Moscow) is the journal that includes research papers in all fields of biochemistry as well as biochemical aspects of molecular biology, bioorganic chemistry, microbiology, immunology, physiology, and biomedical sciences. Coverage also extends to new experimental methods in biochemistry, theoretical contributions of biochemical importance, reviews of contemporary biochemical topics, and mini-reviews (News in Biochemistry).
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