title: Stability and binding properties of a modified thrombin binding aptamer.
abstract: Aptamer-based drugs represent an attractive approach in pharmacological therapy. The most studied aptamer, thrombin binding aptamer (TBA), folds into a well-defined quadruplex structure and binds to its target with good specificity and affinity. Modified aptamers with improved biophysical properties could constitute a new class of therapeutic aptamers. In this study we show that the modified thrombin binding aptamer (mTBA), (3')GGT(5')-(5')TGGTGTGGTTGG(3'), which also folds into a quadruplex structure, is more stable than its unmodified counterpart and shows a higher thrombin affinity. The stability of the modified aptamer was investigated using differential scanning calorimetry, and the energetics of mTBA and TBA binding to thrombin was characterized by means of isothermal titration calorimetry (ITC). ITC data revealed that TBA/thrombin and mTBA/thrombin binding stoichiometry is 1:2 for both interactions. Structural models of the two complexes of thrombin with TBA and with mTBA were also obtained and subjected to molecular dynamics simulations in explicit water. Analysis of the models led to an improvement of the understanding of the aptamer-thrombin recognition at a molecular level.
authors: Dipartimento di Scienze Farmaceutiche, Università di Salerno, Fisciano, Salerno, Italy.
authors: Bruno
authors: B
authors: Pagano
authors: Luigi
authors: L
authors: Martino
authors: Antonio
authors: A
authors: Randazzo
authors: Concetta
authors: C
authors: Giancola
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009691:Nucleic Acid Denaturation; D011485:Protein Binding; D013816:Thermodynamics; D013917:Thrombin / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors; D017186:Titrimetry
chemical_list: D052157:Aptamers, Nucleotide; C081676:thrombin aptamer; D004247:DNA; D013917:Thrombin