Blauer G, Akkawi M
Department of Biological Chemistry, Hebrew University, Jerusalem, Israel.
J Inorg Biochem. 1997 May 1;66(2):145-52. doi: 10.1016/s0162-0134(96)00200-0.
The preparation from ferriprotoporphyrin IX (FP) in aqueous acid medium of the related pigments beta- and B-hematin [see G. Blauer and M. Akkawi, Biochem. Mol. Biol. Int. 35, 231 (1995)] is presented under different conditions. Both pigments are characterized by infrared spectra which differ in the range of 1600-1700 cm-1 in their strong bands with absorption peaks measured at 1648 +/- 2 cm-1 for B-hematin and at 1663 +/- 1 cm-1 for beta-hematin. The pH dependence of B-hematin formation at 37 degrees C and at different concentrations of acetic acid and FP exhibits a maximum yield near pH 4. The formation of beta-hematin at 70 degrees C shows high yield in 6 M acetic acid or in the presence of 0.028 M trichloroacetate at pH 4.6. The dependence of the yield of the pigments on the time and temperature of incubation, concentration of FP, and the presence of different electrolytes was investigated. Both B- and beta-hematin are either insoluble or very slightly soluble in different solvents at room temperature, and appear to dissociate into regular FP in strongly alkaline aqueous medium. In the presence of different quinoline-based drugs, the formation of both B- and beta-hematin at pH 4-5 is inhibited. Under certain conditions, the effect of added carboxylic acids on pigment formation is suggested to be due, at least in part, to the prevention of initial hydrogen bonding among FP carboxyl groups. For both B- and beta-hematin, branched and cyclic macromolecular structures are proposed involving linkages between an FP iron and a side-chain carboxylate group of another FP, in addition to hydrogen bonds between FP carboxyl groups. B- and beta-hematin are assumed to differ in molecular weight and the extent of bond formation. Possible mechanisms for beta-hematin production from B-hematin and certain relations between the synthetic pigments and the malaria pigment are suggested.
介绍了在不同条件下，于酸性水介质中由铁原卟啉IX（FP）制备相关色素β-血红素和B-血红素的方法[见G. Blauer和M. Akkawi，《生物化学与分子生物学国际杂志》35, 231 (1995)]。两种色素的红外光谱特征在于，在1600 - 1700 cm-1范围内，其强吸收带不同，B-血红素的吸收峰在1648±2 cm-1处，β-血红素的吸收峰在1663±1 cm-1处。37℃时，在不同浓度的乙酸和FP存在下，B-血红素形成的pH依赖性在pH 4附近呈现最大产率。70℃时，在6 M乙酸中或在pH 4.6的0.028 M三氯乙酸存在下，β-血红素的形成产率较高。研究了色素产率对孵育时间和温度、FP浓度以及不同电解质存在的依赖性。B-血红素和β-血红素在室温下于不同溶剂中要么不溶，要么溶解度非常低，并且在强碱性水介质中似乎会解离成规则的FP。在不同喹啉类药物存在下，pH 4 - 5时B-血红素和β-血红素的形成均受到抑制。在某些条件下，添加的羧酸对色素形成的影响至少部分归因于防止FP羧基之间最初的氢键形成。对于B-血红素和β-血红素，除了FP羧基之间的氢键外，还提出了涉及一个FP铁与另一个FP侧链羧酸盐基团之间连接的支链和环状大分子结构。推测B-血红素和β-血红素在分子量和键形成程度上存在差异。提出了由B-血红素生成β-血红素的可能机制以及合成色素与疟色素之间的某些关系。
