Biophysical interaction between self-assembled branched DNA nanostructures with bovine serum albumin and bovine liver catalase.

Branched DNA (bDNA) nanostructures have emerged as self-assembled biomaterials and are being considered for biomedical applications. Herein, we report the biophysical interaction between self-assembled bDNA nanostructure with circulating protein bovine serum albumin (BSA) and cellular enzyme bovine liver catalase (BLC). The binding between bDNA and BSA or BLC was confirmed through the decrease in fluorescence spectra. The Stern-Volmer data supports for non-covalent bonding with ~1 binding site in case of BSA and BLC thus advocating a static binding. Furthermore, FTIR and ITC study confirmed the binding of bDNAs with proteins through hydrogen bonding and van der Waals interaction. The negative free energy observed in ITC represent spontaneous reaction for BLC-bDNA interaction. The biophysical interaction between bDNA nanostructures and proteins was also supported by DLS and zeta potential measurement. With an increase in bDNA concentrations up to 100 nM, no significant change in absorbance and CD spectra was observed for both BLC and BSA which suggests structural stability and unaffected secondary conformation of proteins in presence of bDNA. Furthermore, the catalytic activity of BLC was unaltered in presence of bDNAscr even with increasing the incubation period from 1 h to 24 h. Interestingly, the time-dependent decrease in activity of BLC was protected by bDNAmix. The thermal melting study suggests a higher Tm value for proteins in presence of bDNAmix which demonstrates that interaction with bDNAmix increases the thermal stability of proteins. Collectively these data suggest that self-assembled DNA nanostructure may bind to BSA for facilitating circulation in plasma or binding to intracellular proteins like BLC for stabilization, however the secondary conformation of protein or catalytic activity of enzyme is unaltered in presence of bDNA nanostructure. Thus, the newly established genomic sequence-driven self-assembled DNA nanostructure can be explored for in vitro or in vivo experimental work in recent future.