Strasser R J, Butler W L
Biochim Biophys Acta. 1977 Nov 17;462(2):307-13. doi: 10.1016/0005-2728(77)90129-3.
Fluorescence emission spectra excited at 514 and 633 nm were measured at -196 degrees C on dark-grown bean leaves which had been partially greened by a repetitive series of brief xenon flashes. Excitation at 514 nm resulted in a greater relative enrichment of the 730 nm emission band of Photosystem I than was obtained with 633 nm excitation. The difference spectrum between the 514 nm excited fluorescence and the 633 nm excited fluorescence was taken to be representative of a pure Photosystem I emission spectrum at -196 degrees C. It was estimated from an extrapolation of low temperature emission spectra taken from a series of flashed leaves of different chlorophyll content that the emission from Photosystem II at 730 nm was 12% of the peak emission at 694 nm. Using this estimate, the pure Photosystem I emission spectrum was subtracted from the measured emission spectrum of a flashed leaf to give an emission spectrum representative of pure Photosystem II fluorescence at -196 degrees C. Emission spectra were also measured on flashed leaves which had been illuminated for several hours in continuous light. Appreciable amounts of the light-harvesting chlorophyll a/b protein, which has a low temperature fluorescence emission maximum at 682 nm, accumulate during greening in continuous light. The emission spectra of Photosystem I and Photosystem II were subtracted from the measured emission spectrum of such a leaf to obtain the emission spectrum of the light-harvesting chlorophyll a/b protein at -196 degrees C.
在-196℃下，对经一系列重复短暂氙闪光部分变绿的黑暗生长的菜豆叶片，测量了在514和633nm激发下的荧光发射光谱。与633nm激发相比，514nm激发导致光系统I的730nm发射带相对富集程度更高。514nm激发荧光与633nm激发荧光之间的差异光谱被视为-196℃下纯光系统I发射光谱的代表。根据对一系列不同叶绿素含量的闪光叶片低温发射光谱的外推估计，光系统II在730nm处的发射是694nm处峰值发射的12%。利用这一估计值，从闪光叶片的测量发射光谱中减去纯光系统I发射光谱，得到-196℃下代表纯光系统II荧光的发射光谱。还对在连续光照下照射数小时的闪光叶片测量了发射光谱。在连续光照下变绿过程中，会积累大量在682nm处有低温荧光发射最大值的捕光叶绿素a/b蛋白。从这种叶片的测量发射光谱中减去光系统I和光系统II的发射光谱，以获得-196℃下捕光叶绿素a/b蛋白的发射光谱。
