Bohle D Scott, Kosar Andrew D, Madsen Sara K
Department of Chemistry, University of Wyoming, Laramie, WY 82071-3838, USA.
Biochem Biophys Res Commun. 2002 May 31;294(1):132-5. doi: 10.1016/S0006-291X(02)00453-9.
Malaria pigment, or beta-hematin, the insoluble heme detoxification product resulting from the intraerythrocitic digestion of hemoglobin by young malaria trophozoites has been structurally characterized by X-ray powder diffraction and shown to contain chains of propionic acid linked dimers. Although there is considerable spectroscopic evidence for a monodentate propionate-iron interaction in this crystalline material, the spectroscopic characterization of the propionic acid dimer is limited. Herein we demonstrate the presence of the propionic acid dimer unit by H/D isotope substitution in carboxylic acid dimer. In the Raman spectrum of the deuterium substituted compound there is a circa 12 cm(-1) shift, H: 1629 cm(-1) vs. D: 1617 cm(-1) in the symmetric ring breathing mode for the propionic acid dimer. On the other hand, the IR active asymmetric stretch has a very small shift, <3 cm(-1), upon deuteration. These, and other vibrational data, are consistent with the presence of a planar carboxylic acid dimer in the structure of beta-hematin.
疟色素，即β-血红素，是年轻疟原虫滋养体在红细胞内消化血红蛋白产生的不溶性血红素解毒产物，已通过X射线粉末衍射对其结构进行了表征，并显示其含有由丙酸连接的二聚体链。尽管有大量光谱证据表明在这种晶体材料中存在单齿丙酸-铁相互作用，但丙酸二聚体的光谱表征有限。在此，我们通过羧酸二聚体中的氢/氘同位素取代证明了丙酸二聚体单元的存在。在氘取代化合物的拉曼光谱中，对于丙酸二聚体的对称环呼吸模式，有大约12 cm⁻¹的位移，H：1629 cm⁻¹ 对比 D：1617 cm⁻¹。另一方面，红外活性不对称伸缩在氘代后位移非常小，<3 cm⁻¹。这些以及其他振动数据与β-血红素结构中存在平面羧酸二聚体一致。
