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Complexes of Natural / Size–expanded Base Pairs with Small Gold ClustersAuthors: Sandhya Rai,Harjinder Singh,U Deva Priyakumar Conference: Annual Conference of Indian Biophysical Society entitled "Molecular Architecture, Dynamics and Assembly in Living Systems" (MADALS 2014 2014) Location SINP Kolkata Date: 2014-02-07 Report no: IIIT/TR/2014/80 AbstractIn pursuit of exploring new therapeutic and biotechnological applications of alternative genetic systems, use of modified analogues of DNA as templates for growing nanoparticle complexes has increased significantly in recent years. Towards this larger goal, investigation of gold nanoclusters tagged with natural and size–expanded nucleic acid base pairs has generated considerable interest. In this study we have computationally investigated the interaction of natural and size–expanded base pairs with gold cluster (Au3) to understand the nature of the interactions, alongwith their influence on the hydrogen bonding patterns of the base pairs. Based on the density functional calculations performed at PBE0/SDD∪6-311++G(2d,2p) level, it was found that the nature of anchoring bond formed between N/O–Au is non-covalent in nature. It has been observed that, insertion of gold cluster modifies the hydrogen bonding patterns of the base pairs resulting in observable changes in geometry. The interaction with cluster tends to decrease the HOMO-LUMO gaps and expands the spatial distribution of electron wave functions, which makes these complexes more liable for charge transfer. The natural bond orbital (NBO) analysis suggested that the HOMO and LUMO of complexes are localized on the gold cluster suggesting that the electron attachment as well as the ionization processes will take place at the gold cluster without affecting the base pair. The natural population analysis (NPA) indicated that on tagging gold at the N3 site of adenine or guanine and their size-expanded forms, Hoogsteen edge of base pairs becomes a suitable site for further higher order interactions through hydrogen bond formation providing a good platform for designing molecular electronic devices. Full paper: pdf Centre for Computational Natural Sciences and Bioinformatics |
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