The effect of rare earth ion Er 3+ on myoglobin(Mb) was studied by using Resonance Raman spectroscopy. The results show that with the variation of Er 3+ concentrations, both the oxidation state and spin state of Mb are sensitive to the perturbation of Er 3+ . Er 3+ added to Mb affects the oxidation and spin state synchronously. The structure sensitive groups of Mb are more accessible to the Er 3+ than other groups. According to the fluorometry and CD spectra studied and our results as mentioned above, we considered that Er 3+ does not interact with heme directly, and Er 3+ probably leads to the conformational changes of Mb due to the change of oxidation and spin state of Heme. [WT5HZ]
