title: Analysis of telomerase by the telomeric hemin/G-quadruplex-controlled aggregation of au nanoparticles in the presence of cysteine.
abstract: Telomeres are guanosine-rich nucleic-acid chains that fold, in the presence of K(+) ions and hemin, into the telomeric hemin/G-quadruplex structure, exhibiting horseradish peroxidase mimicking functions. The telomeric hemin/G-quadruplex structures catalyze the oxidation of thiols (e.g., l-cysteine) into disulfides (e.g., cystine). As l-cysteine stimulates the aggregation of Au nanoparticles (NPs), accompanied by absorbance changes from red (individual Au NPs) to blue (aggregated Au NPs), the process is implemented to quantitatively analyze the activity (content) of telomerase, a versatile biomarker for cancer cells. Telomerase extracted from 293T cancer cells catalyzes, in the presence of a dNTPs mixture and an appropriate primer probe, the telomerization process, leading to the generation of catalytic telomeric hemin/G-quadruplex chains that control the l-cysteine-mediated aggregation of Au NPs. The extent of aggregation is thus controlled by the concentration of telomerase. The method enabled the detection of telomerase with a detection limit of 27 cells/μL. The spectral changes accompanying the aggregation of Au NPs are further supported by transmission electron microscopy imaging.
authors: Institute of Chemistry, The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem , Jerusalem 91904, Israel.
authors: Etery
authors: E
authors: Sharon
authors: Eyal
authors: E
authors: Golub
authors: Angelica
authors: A
authors: Niazov-Elkan
authors: Dora
authors: D
authors: Balogh
authors: Itamar
authors: I
authors: Willner
mesh_terms: D003545:Cysteine / Q000378:metabolism*; D054856:G-Quadruplexes; D006427:Hemin / Q000378:metabolism*; D053758:Nanoparticles; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*
chemical_list: D006427:Hemin; D019098:Telomerase; D003545:Cysteine