Centro de Ciências Exatas e Tecnológicas
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/9791
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2 resultados
Resultados da Pesquisa
Item DNA Interaction with diaminobenzidine studied with optical tweezers and dynamic light scattering(The Journal of Physical Chemistry B, 2013-10-28) Reis, L. A.; Ramos, E. B.; Rocha, M. S.We have studied the interaction of the DNA molecule with the ligand 3,3′-diaminobenzidine (DAB) by performing single molecule stretching experiments with optical tweezers and dynamic light scattering (DLS) on the DNA−DAB complexes. In the stretching experiments, the persistence and contour lengths of the complexes were measured as a function of DAB concentration, allowing one to infer the main binding mechanism and also to determine the physicochemical parameters of the interaction. In the DLS experiments, the effective size of the complexes, measured as the hydrodynamic radius, was monitored as a function of DAB concentration. We found a qualitative agreement between the results obtained from the two techniques by comparing the behaviors of the hydrodynamics radius and the radius of gyration, since this last one can be expressed as a function of the persistence and contour lengths.Item DNA interaction with DAPI fluorescent dye: Force spectroscopy decouples two different binding modes(Biopolymers, 2017-01-18) Reis, L. A.; Rocha, M. S.In this work, we use force spectroscopy to investigate the interaction between the DAPI fluorescent dye and the k-DNA molecule under high (174 mM) and low (34 mM) ionic strengths. Firstly, we have measured the changes on the mechanical properties (persistence and contour lengths) of the DNA-DAPI complexes as a function of the dye concentration in the sample. Then, we use recently developed models in order to connect the behavior of both mechanical properties to the physical chemistry of the interaction. Such analysis has allowed us to identify and to decouple two main binding modes, determining the relevant physicochemical (binding) parameters for each of these modes: minor groove binding, which saturates at very low DAPI concentrations (C T 0.50 lM) and presents equilibrium binding constants of the order of 10 7 M 21 for the two ionic strengths studied; and intercalation, which starts to play a significant role only after the saturation of the first mode, presenting much smaller equilibrium binding constants ( 10 5 M 21 ).