Probing Protein Kinase (CK2) and Alkaline Phosphatase with CdSe/ZnS Quantum Dots

• Published in: Nano letters 2010-06, Vol.10 (6), p.2192-2196
• Main Authors: Freeman, Ronit, Finder, Tali, Gill, Ron, Willner, Itamar
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase - chemistry; Alkaline Phosphatase - metabolism; Applied sciences; Biocatalysis; Cadmium Compounds - chemistry; Casein Kinase II - chemistry; Casein Kinase II - metabolism; Catalytic methods; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Fluorescence Resonance Energy Transfer; Hydrolysis; Materials science; Methods of nanofabrication; Molecular electronics, nanoelectronics; Molecular Probes; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Phosphorylation; Physics; Quantum Dots; Selenium Compounds - chemistry; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Spectrum Analysis; Sulfides - chemistry; Zinc Compounds - chemistry
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl101052f

Semiconductor quantum dots (QDs) are used for the optical analysis of casein kinase (CK2) or the hydrolytic activity of alkaline phosphatase (ALP). Two schemes for the analysis of CK2 by a FRET-based mechanism are described. One approach involves the CK2-catalyzed phosphorylation of a serine-containing peptide (1), linked to CdSe/ZnS QDs, with Atto-590-functionalized ATP. The second analytical method involves the specific association of the Atto-590-functionalized antibody to the phosphorylated product. The hydrolytic activity of ALP is followed by the application of phosphotyrosine (4)-modified CdSe/ZnS QDs in the presence of tyrosinase as a secondary reporter biocatalyst. The hydrolysis of (4) yields the tyrosine units that are oxidized by O2/tyrosinase to the respective dopaquinone product. The latter quinone units quench the QDs via an electron transfer route, leading to the optical detection of the ALP activity.