A 12-Porphyrin System: Syntheses of Peptide Porphyrins with Multiple Histidines and the Aggregation Behavior in the Presence of Hemin
作者:Masato Ushiyama、Atsushi Yoshino、Takeshi Yamamura、Yasuo Shida、Fumio Arisaka
DOI:10.1246/bcsj.72.1351
日期:1999.6
We succeeded in combining multiple-histidine peptides with porphyrins; that is to say, we synthesized three peptide porphyrins consisting of α4-meso-tetrakis(o-aminophenyl)porphyrin, α4-H2TAPP, and amphiphilic peptide, α4-(PepA18)n(AG)4−n-H2TAPP (n = 1, 3, and 4; PepA18 = EEALEKHEKALEKHEKAG), in the liquid phase. These compounds were designed to construct multiple porphyrin systems; in other words, each peptide attached on the H2TAPP was designed to contain two histidines. The stability of the porphyrins, (AG)4-H2TAPP and (AG)1(Boc-AG)3-H2TAPP, as well as the coupling conditions between the porphyrin fragments and the 16-residue peptide, EEALEKHEKALEKHEK, to give α4-(PepA18)n(AG)4−n-H2TAPP (n = 1, 3, and 4) were studied in detail with respect to the temperature, solvents, coupling reagents, additives, and amines. This search revealed that the combination of DMF/benzotriazol-1-yl-oxy-tris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP)/N,N-diisopropylethylamine is suitable for the purpose. The search also clarified that it is possible to synthesize α4-(PepA18)4-H2TAPP and α4-(PepA18)3(AG)1-H2TAPP selectively by choosing the coupling additives 1-hydroxy-7-azabenzotriazole (HOAt) and 1-hydroxybenzotriazole (HOBt), respectively.All of the compounds showed 40% helicity in a solution (phospate buffer, pH = 7.0) containing 2,2,2-trifluoroethanol (TFE). The UV-vis and circular-dichroism spectrophotometric titrations of Fe(III) protoporphyrin IX chloride, B, with α4-(PepA18)4-ZnTAPP, A, indicated that up to three equivalents of B were incorporated into A in a buffer solution containing 15% TFE. Sedimentation-equilibrium ultracentrifugation experiments showed that A is a dimer in the solution, and that this dimer is transformed to a trimer when B is incorporated into A. These results suggest that A achieves a 12-porphyrin system consisting of different kinds of metalloporphyrin.
我们成功地将多组氨酸肽与卟啉结合,即在液相中合成了三种由α4-均四(邻氨基苯基)卟啉、α4-H2TAPP和两亲性肽组成的肽卟啉,α4-(PepA18)n(AG)4−n-H2TAPP(n=1,3,4;PepA18=EEALEKHEKALEKHEKAG)。这些化合物旨在构建多卟啉体系;换言之,每个附着在H2TAPP上的肽段设计为含有两个组氨酸。针对温度、溶剂、偶联试剂、添加剂和胺,详细研究了卟啉的稳定性,(AG)4-H2TAPP和(AG)1(Boc-AG)3-H2TAPP,以及卟啉片段与16残基肽,EEALEKHEKALEKHEK之间的耦合条件,以生成α4-(PepA18)n(AG)4−n-H2TAPP(n=1,3,4)。研究发现,DMF/苯并三唑-1-基氧基三(吡咯烷基)磷鎓六氟磷酸盐(PyBOP)/N,N-二异丙基乙胺的组合适用于此目的。研究还阐明,通过选择偶联添加剂1-羟基-7-氮杂苯并三唑(HOAt)和1-羟基苯并三唑(HOBt),可以有选择性地合成α4-(PepA18)4-H2TAPP和α4-(PepA18)3(AG)1-H2TAPP。所有化合物在含有2,2,2-三氟乙醇(TFE)的溶液(磷酸盐缓冲液,pH=7.0)中均显示出40%的螺旋度。Fe(III)原卟啉IX氯化物B与α4-(PepA18)4-ZnTAPP,A的紫外-可见光和圆二色光谱滴定表明,在含有15% TFE的缓冲溶液中,最多可掺入三个当量的B到A中。沉降平衡超速离心实验显示,A在溶液中为二聚体,当B掺入A时,该二聚体转变为三聚体。这些结果表明,A实现了由不同金属卟啉组成的12卟啉体系。