Spectroscopic and computational insight into the conformational dynamics of hemoglobin in the presence of vitamin B12.

Protein-ligand interactions play a significant role in all living organisms, thereby affecting the design and application of drugs and other biomaterials. The current study reports the binding of vitamin B12 to hemoglobin, employing optical spectroscopy and computational methods. It is observed that vitamin B12 quenched the intrinsic fluorescence of hemoglobin. The nature of quenching appears to be static according to the steady-state and time-resolved fluorescence measurements. The conformational changes of hemoglobin caused by vitamin B12 interactions were studied by synchronous fluorescence spectroscopy and protein secondary structure analyses. The synchronous fluorescence spectra indicate the tryptophan residue microenvironment change while no secondary structural change is observed from circular dichroism spectra and molecular dynamics (MD) simulation study. The computational molecular docking elucidated the probable binding of vitamin B12 at the active site of hemoglobin, whereas the stability of the hemoglobin-vitamin B12 complex was studied by MD simulation. The study might be helpful for the treatment of pernicious anemia, hereditary transcobalamin deficiency, and performance enhancement of elite athletes.