Local structure of highly dispersed lead containing zeolite. An ab initio and density functional theory study

Quantification and Improvement of the Dynamics of Human Serum Albumin and Glycated Human Serum Albumin with Astaxanthin/Astaxanthin-Metal Ion Complexes: Physico-Chemical and Computational Approaches

Glycated human serum albumin (gHSA) undergoes conformational changes and unfolding events caused by free radicals. The glycation process results in a reduced ability of albumin to act as an endogenous scavenger and transporter protein in diabetes mellitus type 2 (T2DM) patients. Astaxanthin (ASX) in native form and complexed with metal ions (Cu²⁺ and Zn²⁺) has been shown to prevent gHSA from experiencing unfolding events. Furthermore, it improves protein stability of gHSA and human serum albumin (HSA) as it is shown through molecular dynamics studies. In this study, the ASX/ASX-metal ion complexes were reacted with both HSA/gHSA and analyzed with electronic paramagnetic resonance (EPR) spectroscopy, rheology and zeta sizer (particle size and zeta potential) analysis, circular dichroism (CD) spectroscopy and UV-Vis spectrophotometer measurements, as well as molecular electrostatic potential (MEP) and molecular docking calculations. The addition of metal ions to ASX improves its ability to act as an antioxidant and both ASX or ASX-metal ion complexes maintain HSA and gHSA stability while performing their functions.

DFT and molecular dynamics studies of astaxanthin-metal ions (Cu2+ and Zn2+) complex to prevent glycated human serum albumin from possible unfolding

Glycated human serum albumin (gHSA) undergoes conformational changes of proteins caused by free radicals. The glycation process results in a reduced ability of albumin as an endogenous scavenger in diabetes mellitus type 2 (T2DM) patients. Astaxanthin (ASX) has been shown to prevent gHSA from experiencing unfolding events and improve protein stability of gHSA and HSA through molecular dynamics. In this study, astaxanthin is complexed with transition metal ions such as copper (Cu²⁺) and zinc (Zn²⁺) in two modes (M) and (2M). Complexing astaxanthin with Cu²⁺ and Zn²⁺ is expected to increase astaxanthin's ability as an endogenous scavenger than in native form. This research aims to characterize the antiradical property of ASX, ASX-Cu²⁺ and ASX-2Cu²⁺, ASX-Zn²⁺, and ASX-2Zn²⁺ with density functional theory (DFT) and to compare the capability to prevent conformational changes on glycated albumin through molecular dynamics simulation. DFT as implemented in Gaussian 09W, was used for all calculations. Analysis of data using GaussView 6.0. LANL2D2Z basis set and B3LYP density functional used for frequency analysis and optimization. The AutoDock Vina implemented in PyRx 0.8 is used to and receptor-ligand interactions analysis with the DS 2016 Client. YASARA for molecular dynamic simulation with 15,000 ps as running time. DFT analyzes such as energy gaps, HOMO, and LUMO patterns and electronic properties have shown that ASX-metal ions complex is better than ASX in native state as antioxidants. These results are also supported by the molecular dynamics simulation (RMSD backbone, RMSDr, RMSFr, and movie visualization), where the addition of ASX-metal ions complex on gHSA are better than ASX as a single compound in preventing gHSA from possible unfolding and maintaining protein molecule stability.

The metal cation chelating capacity of astaxanthin. Does this have any influence on antiradical activity?

In this Density Functional Theory study, it became apparent that astaxanthin (ASTA) may form metal ion complexes with metal cations such as Ca⁺², Cu⁺², Pb⁺², Zn⁺², Cd⁺² and Hg⁺². The presence of metal cations induces changes in the maximum absorption bands which are red shifted in all cases. Therefore, in the case of compounds where metal ions are interacting with ASTA, they are redder in color. Moreover, the antiradical capacity of some ASTA-metal cationic complexes was studied by assessing their vertical ionization energy and vertical electron affinity, reaching the conclusion that metal complexes are slightly better electron donors and better electron acceptors than ASTA.