Interaction Between Neuroglobin and Caffeine by Multispectroscopic Methods

The interaction between neuroglobin (Ngb) and caffeine was studied by spectroscopy. UV-Vis spectra revealed that caffeine did not influence the native hexa-coordinated heme structure of neuroglobin. Fluorescence spectra indicated that caffeine could quench the intrinsic fluorescence of neuroglobin through static quenching mechanisms. The calculated thermodynamic parameters showed that the electrostatic force was the main intermolecular force in the reaction. Results also indicated that the microenvironmental changes of tryptophan and tyrosine residues within neuroglobin are inapparent. Furthermore, the circular dichroism (CD) spectra implied that caffeine could induce the formation of α-helix structure of neuroglobin.