Interaction between cytochrome c and the hapten 2,4-dinitrofluorobenzene by electrospray ionization mass spectrometry

Allergic contact, dermatitis is a delayed hypersensitivity reaction, which results from skin exposure to low molecular weight chemicals such as haptens. To clarify the pathogenic mechanism, electrospray ionization mass spectrometry (ESI-MS) and hydrogen/deuterium (H/D) exchange, as well as UV spectroscopy, were applied to determine the interaction between the model protein cytochrome c (cyt c) and the hapten 2,4-dinitro-fluorobenzene (DNFB). The ESI-MS results demonstrate that the conformation of cyt c can change front native folded state into partially unfolded state with the increase of DNFB. The equilibrium state H/D exchange followed by EST-MS further confirms the above results. UV spectroscopy indicates that the strong-field coordination between iron of heme (prosthetic group) and His18 or Met80 of cyt c is riot obviously affected by the hapten.