Lower-energy photons do the work, too Plants and cyanobacteria use chlorophyll-rich photosystem complexes to convert light energy into chemical energy. Some organisms have developed adaptations to take advantage of longer-wavelength photons. Nürnberg et al. studied photosystem complexes from cyanobacteria grown in the presence of far-red light. The authors identified the primary donor chlorophyll as one of a few chlorophyll molecules in the far-red light–adapted enzymes that were chemically altered to shift their absorption spectrum. Kinetic measurements demonstrated that far-red light is capable of directly driving water oxidation, despite having less energy than the red light used by most photosynthetic organisms. Science, this issue p. 1210 A chlorophyll variant with far-red absorption is involved in photosynthesis in cyanobacteria adapted to far red light. Photosystems I and II convert solar energy into the chemical energy that powers life. Chlorophyll a photochemistry, using red light (680 to 700 nm), is near universal and is considered to define the energy “red limit” of oxygenic photosynthesis. We present biophysical studies on the photosystems from a cyanobacterium grown in far-red light (750 nm). The few long-wavelength chlorophylls present are well resolved from each other and from the majority pigment, chlorophyll a. Charge separation in photosystem I and II uses chlorophyll f at 745 nm and chlorophyll f (or d) at 727 nm, respectively. Each photosystem has a few even longer-wavelength chlorophylls f that collect light and pass excitation energy uphill to the photochemically active pigments. These photosystems function beyond the red limit using far-red pigments in only a few key positions.

中文翻译：

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含有叶绿素 f 的光系统中超出红色极限的光化学

低能光子也能发挥作用 植物和蓝藻使用富含叶绿素的光系统复合物将光能转化为化学能。一些生物体已经开发出适应性来利用更长波长的光子。纽伦堡等。研究了在远红光存在下生长的蓝藻的光系统复合物。作者将主要供体叶绿素鉴定为适应远红光的酶中的少数叶绿素分子之一，这些分子经过化学改变以改变其吸收光谱。动力学测量表明，远红光能够直接驱动水氧化，尽管其能量低于大多数光合生物使用的红光。科学，这个问题 p。1210 具有远红光吸收的叶绿素变体参与了适应远红光的蓝细菌的光合作用。光系统 I 和 II 将太阳能转化为为生命提供动力的化学能。叶绿素 a 光化学，使用红光（680 至 700 nm），几乎是通用的，被认为定义了含氧光合作用的能量“红色极限”。我们展示了在远红光 (750 nm) 下生长的蓝藻光系统的生物物理学研究。存在的少数长波长叶绿素彼此和主要色素叶绿素 a 都能很好地分离。光系统 I 和 II 中的电荷分离分别使用 745 nm 处的叶绿素 f 和 727 nm 处的叶绿素 f（或 d）。每个光系统都有一些甚至更长波长的叶绿素 f ，它们收集光并将激发能量向上传递给光化学活性色素。这些光系统仅在少数几个关键位置使用远红色颜料，其功能超出了红色极限。