Microscopic and spectroscopic study of the corona formation and unfolding of human haemoglobin in presence of ZnO nanoparticles

Quantum dot-protein interface: Interaction of the CdS quantum dot with human hemoglobin for the study of the energy transfer process and binding mechanism along with detection of the unfolding of hemoglobin

In this study, the interaction of the human hemoglobin with cost effective and chemically fabricated CdS quantum dots (QDs) (average sizes ≈3nm) has been investigated. The semiconductor QDs showed maximum visible absorption at 445 nm with excitonic formation and band gap of ≈ 2.88 eV along with hexagonal crystalline phase. The binding of QDs-Hb occurs through corona formation to the ground sate complex formation. The life time of the heme pocket binding and reorganization were found to be t1 = 43 min and t2 = 642 min, respectively. The emission quenching of the Hb has been indicated large energy transfer between CdS QDs and Hb with tertiary deformation of Hb. The binding thermodynamics showed highly exothermic nature. The ultrafast decay during corona formation was studied from TCSPC. The results showed that the energy transfer efficiency increases with the increase of the QDs concentration and maximum ≈71.5 % energy transfer occurs and average ultrafast lifetime varies from 5.45 ns to1.51 ns. The deformation and unfolding of the secondary structure of Hb with changes of the α-helix (≈74 % to ≈51.07 %) and β-sheets (≈8.63 % to ≈10.25 %) have been observed from circular dichroism spectrum. The SAXS spectrum showed that the radius of gyration of CdS QDs-Hb bioconjugate increased (up to 23 ± 0.45 nm) with the increase of the concentration of QDs compare with pure Hb (11 ± 0.23 nm) and Hb becoming more unfolded.

Investigation on intermolecular interaction of synthesized azo dyes with bovine serum albumin

This research was performed using spectroscopic techniques and molecular docking to elucidate the mechanisms of interaction between bovine serum albumin (BSA) and two novel synthesized azo dyes. The titration of dyes into BSA solution results in quenching of fluorescence emission by complex formation. The UV-Vis spectroscopy confirms that formation of complex in ground state between both dyes and BSA induces conformational and micro environmental changes of the protein. Based on the calculation of the thermodynamic parameters, it can be concluded that both dyes spontaneously bind onto BSA, and van der Waals force and hydrogen bonding interaction played a predominant roles in the process of spontaneous bonding. The average binding distance (r) between protein and both dyes was calculated by Förster energy transfer measurements and revealed both dyes bind to the BSA residues of tryptophan over short distances. The results of molecular docking studies indicated that the probable binding location of both dyes is subdomain IB of BSA via hydrophobic interaction and hydrogen bond. Furthermore, as shown by synchronous fluorescence and Fourier transform infrared spectroscopy, both dyes can lead to conformational changes of BSA, which alter its biological functions.Communicated by Ramaswamy H. Sarma.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.