Changes in the secondary and tertiary structure of DNA upon binding to silver, gold, and palladium nanoparticles (NPs) in solution were studied using UV spectroscopy, viscometry, dynamic light scattering, flow birefringence, and atomic force microscopy. A method for preparation of NP bioconjugates with DNA was developed. The enhancement of optical anisotropy of the macromolecule upon its contacts with metal NPs was detected. The effect of the formed structures on the persistence length of DNA and on the volume effects in the system was analyzed. A mechanism of NP formation upon the reduction of DNA-bound metal ions was proposed.