Protein cohesion induced by metal ions observed with fluorescence correlation spectroscopy

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Toxic/hazardous substances & environmental engineering, 2013, Vol.48 (11), p.1311-1317
• Main Authors: Inoue, Kana, Aoki, Motohide, Fujiwara, Kitao
• Format: Article
• Language: English
• Subjects: Aggregates; Antibodies, Monoclonal - chemistry; cohesion; Correlation; Correlation analysis; Denaturation; Dilution; Fluorescence; fluorescence correlation spectroscopy; green fluorescent protein; Green Fluorescent Proteins - chemistry; Humans; Ions; metal ion; Metal ions; Metals - chemistry; Molecules; nitrogen; oxygen; PE-conjugated human antibody protein; phycoerythrin; Phycoerythrin - chemistry; Protein Binding; protein cohesion; Protein denaturation; Proteins; Spectrometry, Fluorescence - methods; Spectroscopy; Spectrum analysis; ZsGreen
• ISSN: 1532-4117; 1093-4529; 1532-4117
• DOI: 10.1080/10934529.2013.781861

Nine metal ions were evaluated in the point of denaturating action of proteins. When some metal ions were added to the diluted protein solutions, aggregates appear: stronger denaturation causes the appearance of the larger-size aggregate. The size of the aggregatates are determined by fluorescence correlation spectroscopy (FCS). Green fluorescent protein (ZsGreen) and PE(phycoerythrin)-conjugated human-antibody monoclonal protein were employed as the target protein, of which solution was diluted 100–500 times and mixed with metal ions. According to this process, the denaturation power of metal ions is in the order of Mn²⁺≈ Fe²⁺< Co²⁺< Ni²⁺< Tl⁺< Cd²⁺< Cu⁺< Cu²⁺< Pb²⁺for ZsGreen, and Tl⁺≈ Ni²⁺< Cd²⁺< Fe²⁺< Cr³⁺≪ Pb²⁺for PE-conjugated antibody protein. Pb²⁺exhibits the strongest power of denaturation. In the case of ZsGreen, the denaturation power of metal ions is on the order of the Irving-Williams series, which provide the coordination tendency against ligands possessing nitrogen and oxygen. The present method with FCS is effective to evaluate the denaturation power of metal ions against proteins.