title: Probing protein kinase (CK2) and alkaline phosphatase with CdSe/ZnS quantum dots.
abstract: 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 O(2)/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.
authors.affiliation: Institute of Chemistry, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Ronit
authors.initials: R
authors.lastname: Freeman
authors.forename: Tali
authors.initials: T
authors.lastname: Finder
authors.forename: Ron
authors.initials: R
authors.lastname: Gill
authors.forename: Itamar
authors.initials: I
authors.lastname: Willner
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry* / Q000378:metabolism; D055162:Biocatalysis; D019187:Cadmium Compounds / Q000737:chemistry*; D047390:Casein Kinase II / Q000737:chemistry* / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D006868:Hydrolysis; D015335:Molecular Probes; D010766:Phosphorylation; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D013057:Spectrum Analysis; D013440:Sulfides / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D015335:Molecular Probes; D018036:Selenium Compounds; D013440:Sulfides; D017967:Zinc Compounds; C058667:cadmium selenide; D047390:Casein Kinase II; D000469:Alkaline Phosphatase; C031238:zinc sulfide