SPECTROSCOPIC STUDIES OF PHYCOBILISOME SUBCORE PREPARATIONS LACKING KEY CORE CHROMOPHORES - ASSIGNMENT OF EXCITED-STATE ENERGIES TO THE L(CM), BETA(18) AND ALPHA(AP-B) CHROMOPHORES
SPECTROSCOPIC STUDIES OF PHYCOBILISOME SUBCORE PREPARATIONS LACKING KEY CORE CHROMOPHORES - ASSIGNMENT OF EXCITED-STATE ENERGIES TO THE L(CM), BETA(18) AND ALPHA(AP-B) CHROMOPHORES
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DOI：
10.1016/0005-2728(94)90174-0
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发表时间：
1994-07-29
影响因子：
4.3
通讯作者：
SAUER, K
中科院分区：
文献类型：
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作者：
GINDT, YM;ZHOU, JH;SAUER, K
利用聚球藻基因工程菌株研究了α(AP-B)、β(18)和L(Cm)(大核膜连接物)发色团在藻胆体核心内的吸收和发射特性。PCC 7002。用稳态发射和时间分辨发射研究了野生型生物和两个突变体亚核制剂中的能量转移。还测量了来自野生型和5个突变菌株的完整藻胆体的低温(77K)发射光谱。保留α(AP-B)亚基或未改变的L(Cm)发色团的突变体仅导致低温发射光谱的微小变化，而仅保留β(18)亚基导致发射光谱蓝移。L(Cm)发色团的室温最大吸收波长为675 nm。在77K的藻胆体中，α(AP-B)和L(Cm)发色团的发射波长为682-683 nm，在室温下也是长波发射体的最佳候选者。这些发射光谱与相关类囊体膜对叶绿素a的吸收重叠在蓝藻天线复合体的激发转移中起着重要作用。
Chromophore absorption and emission characteristics of the alpha(AP-B), beta(18) and L(cm) (large core-membrane linker) chromopeptides within the phycobilisome core are investigated using genetically engineered strains of Synechococcus sp. PCC 7002. Steady-state and time-resolved emission were used to examine energy transfer in subcore preparations from the wild-type organism and two mutants. Low-temperature (77 K) emission spectra were also measured for intact phycobilisomes from the wild-type and five mutant strains. Mutants retaining either the alpha(AP-B) subunit or the unaltered L(cm) chromophore resulted in only small changes in the low-temperature emission spectra, while retention of only the beta(18) subunit resulted in blue-shifted emission spectra. The L(cm) chromophore has a room-temperature absorption maximum at 675 nm. In phycobilisomes at 77 K the alpha(AP-B) and L(cm) chromophores emit at 682-683 nm, and they are the best candidates for long-wavelength emitters also at room temperature. Overlap of these emission spectra with the absorption of chlorophyll a in the associated thylakoid membrane plays a significant role in excitation transfer from the antenna complexes in cyanobacteria.