A colorimetric strategy for assay of protease activity based on gold nanoparticle growth controlled by ascorbic acid and Cu(II)-coordinated peptide
Author：Lin Liu, Dehua Deng, Yiru Wang, Kewei Song, Ziling Shang, Qiao Wang, Ning Xia, Bing Zhang 《Sensors and Actuators B: Chemical》 ABSTRACTS We developed a colorimetric method for assay of protease activity through the growth of gold nanoparticles (AuNPs) with ascorbic acid (AA) as the reducing agent. The method is based on the difference in the catalytic activity of various Cu 2+ species toward AA oxidation. A mutational peptide is employed as the protease substrate, in which only one amino acid residue is replaced by the histidine residue. Specifically, HAuCl 4 can be reduced into AuNPs by AA; Cu 2+ ion promotes the oxidation of AA under oxygen atmosphere by a redox cycling, thus preventing the formation of AuNPs. Cleavage of the substrate peptide results in the exposure of an amino terminal Cu 2+ and Ni 2+ -binding (ATCUN) motif in the NH 2 -terminus of one fragment. The resultant ATCUN peptide can sequestrate Cu 2+ and th...