de Paula J C, Robblee J H, Pasternack R F
Department of Chemistry, Haverford College, Pennsylvania 19041.
Biophys J. 1995 Jan;68(1):335-41. doi: 10.1016/S0006-3495(95)80192-X.
We report the resonance light scattering (RLS) spectra of chlorophyll a aggregated in a 9:1 solution of formamide and pH 6.8 phosphate buffer. The aggregate formed after 2 h of mixing, referred to as Chl469, shows a strong scattering feature at 469 nm (Soret band) and a much weaker feature at 699 nm (Qy band). A kinetic investigation confirmed that the aggregation process is cooperative, and also detected one intermediate (Chl458) with a strong RLS spectrum but only a weak CD spectrum. We propose that aggregation proceeds via at least three steps: 1) formation of a nucleating species, probably a dimer of chlorophylls; 2) formation of large aggregates with little or no secondary structure (e.g., Chl458); and 3) conformational change to form helical aggregate (Chl469).
我们报道了叶绿素a在甲酰胺与pH 6.8磷酸盐缓冲液9:1的溶液中聚集时的共振光散射（RLS）光谱。混合2小时后形成的聚集体，称为Chl469，在469nm处显示出强烈的散射特征（Soret带），在699nm处显示出弱得多的特征（Qy带）。动力学研究证实聚集过程是协同的，并且还检测到一种具有强RLS光谱但只有弱圆二色光谱的中间体（Chl458）。我们提出聚集至少通过三个步骤进行：1）形成成核物种，可能是叶绿素的二聚体；2）形成几乎没有二级结构或没有二级结构的大聚集体（例如Chl458）；3）构象变化以形成螺旋聚集体（Chl469）。
