Design and synthesis of water soluble (metallo)porphyrins with pendant arms: studies of binding to xanthine oxidase
作者:Elizabeth A. Gibson、Anne-K. Duhme-Klair、Robin N. Perutz
DOI:10.1039/b9nj00736a
日期:——
The tethering of a substrate analogue to a covalently attached luminophore may give rise to a probe for reporting enzyme activity spectrofluorometrically. The overall design incorporates a water-soluble porphyrin luminophore, a substrate analogue and a planar conjugated bridge of the appropriate length designed to bind in the substrate-access channel of xanthine oxidase (XO). 5,10,15-Tris(N-methyl-4-pyridiniumyl)-20-phenyl porphyrins was functionalised at the 4-position of the phenyl group with amide-linked 2-methoxy-benzamide groups, [(2-methoxy-4-amino-phenylcarbonyl)-amino] or [(2-methoxy-4-[(pyridine-4-carbonyl)-amino]-phenylcarbonyl)-amino]. The products were isolated as free base or zinc porphyrins with chloride or hexafluorophosphate counterions and characterised by optical emission and absorption in addition to other spectroscopic methods. Binding studies of bovine XO to the zinc porphyrin trichloride derivatives with the above linkers were used to determine the IC50 of 81 and 113 μM and Ki values of 4.6 and 6.5 μM, respectively. Furthermore, addition of XO to an aqueous solution of the products caused quenching of the porphyrin emission and a red shift in the absorption spectrum.
底物类似物与共价连接的发光团的束缚可以产生用于通过荧光光谱法报告酶活性的探针。总体设计包含水溶性卟啉发光团、底物类似物和适当长度的平面共轭桥,旨在结合黄嘌呤氧化酶 (XO) 的底物进入通道。 5,10,15-三(N-甲基-4-吡啶鎓基)-20-苯基卟啉在苯基的4位上用酰胺连接的2-甲氧基-苯甲酰胺基团进行功能化,[(2-甲氧基-4 -氨基-苯基羰基)-氨基]或[(2-甲氧基-4-[(吡啶-4-羰基)-氨基]-苯基羰基)-氨基]。产品被分离为游离碱或锌卟啉与氯或六氟磷酸盐抗衡离子,并通过光学发射和吸收以及其他光谱方法进行表征。牛 XO 与具有上述接头的三氯化锌卟啉衍生物的结合研究用于确定 IC50 分别为 81 和 113 μM,Ki 值分别为 4.6 和 6.5 μM。此外,将XO添加到产物的水溶液中导致卟啉发射的猝灭和吸收光谱的红移。