Enzyme-targeted fluorescent imaging probes on a multiple antigenic peptide core
Enzyme-targeted fluorescent imaging probes on a multiple antigenic peptide core
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DOI：
10.1021/jm051001a
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发表时间：
2006-07-27
影响因子：
7.3
通讯作者：
Tung, Ching-Hsuan
中科院分区：
文献类型：
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作者：
Galande, Amit K.;Hilderbrand, Scott A.;Tung, Ching-Hsuan
肽树枝状聚合物在生物学中具有多种应用，例如用于药物和基因递送的载体、分子抑制剂、蛋白质模拟物和合成疫苗。多抗原肽（MAP）系统是离散的树枝状聚合物支架的众所周知的实例。我们通过设计仅在酶处理后才发荧光的分子探针，探索了基于MAP的支架的新应用。在固体支持物上合成的探针将组织蛋白酶S二肽底物（Leu-Arg）和聚（乙二醇）（PEG）链结合在其树枝状臂中。近红外荧光染料连接到树枝状臂的N-末端的荧光发射被淬灭。机制研究表明，形成H型染料聚集体内的四价MAP系统。通过改变PEG链的长度，合成了三种探针，分别具有4、8和12个环氧乙烷单元的CyPEG-1、CyPEG-2和CyPEG-3。CyPEG-2显示出最佳的水溶性和成像应用的猝灭效率。在用组织蛋白酶S（EC 3.4.22.27）蛋白水解活化后，CyPEG-2显示荧光发射的大于70倍的增加和大于95%的恢复。
Peptide dendrimers have a variety of applications in biology such as the vehicles for drug and gene delivery, molecular inhibitors, protein mimics, and synthetic vaccines. The multiple antigenic peptide (MAP) system is a well-known example of a discrete, dendrimeric scaffold. We explored a novel application of the MAP-based scaffold by designing molecular probes that fluoresce only after enzymatic treatment. The probes, which were synthesized on solid support, incorporate a cathepsin S dipeptide substrate (Leu-Arg), and a poly(ethylene glycol) (PEG) chain in their dendritic arms. The fluorescence emission of the near-infrared fluorochromes attached to the N-termini of the dendritic arms was quenched. Mechanistic studies revealed formation of H-type dye aggregates within the tetravalent MAP system. By varying the length of the PEG chain, three probes were synthesized, CyPEG-1, CyPEG-2, and CyPEG-3 with 4, 8, and 12 ethylene oxide units, respectively. CyPEG-2 showed optimum aqueous solubility and quenching efficiency for imaging applications. Upon proteolytic activation with cathepsin S (EC 3.4.22.27), CyPEG-2 showed greater than 70-fold increase and more than 95% recovery in fluorescence emission.