Label-free detection of telomerase activity using guanine electrochemical oxidation signal


ESKIOCAK U., Ozkan-Ariksoysal D. , OZSOZ M., OKTEM H. A.

ANALYTICAL CHEMISTRY, cilt.79, ss.8807-8811, 2007 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 79 Konu: 22
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1021/ac071014r
  • Dergi Adı: ANALYTICAL CHEMISTRY
  • Sayfa Sayıları: ss.8807-8811

Özet

Telomerase is an important biomarker for cancer cells and its activation in 85% of all cancer types confers a clinical diagnostic value. A label-free electrochemical assay based on guanine oxidation signal to measure telomerase activity is described. This developed technology combined with a disposable sensor, carbon graphite electrode (CGE), and differential pulse voltammetry (DPV) was performed by using PCR amplicons with/without telomeric repeats as the guanine oxidation signal observed at +1.0 V measured after the immobilization of PCR products. Guanine oxidation signal was chosen as a measure of telomerase activity because a substantial increase in the number of guanines was introduced by the action of telomerase which adds hexameric repeats (TTAGGG)(n) that contain 50% guanine. The developed assay was shown to specifically measure telomerase activity from cell extracts, and elongation rates increased linearly in a concentration dependent manner. Telomerase activity could be detected in cell extracts containing as low as 100 ng/mu L of protein. All of the electrochemical measurements were also confirmed with the conventional TRAP-silver staining assay. Rapidity, simplicity, and the label-free nature of the developed assay make it suitable for practical use in quantitative determination of telomerase activity from clinical samples for diagnosis of cancer.