| Azurin, a bacterial redox cell protein from Pseudomonas Alcaligenes, is a low molecular weight copper protein, it has redox ability and electron tansfer function in organism. Previously the study focused on its molecule configuration and structure. But in recent years it was found that azurin can form a complex with tumor inhibit protein p53, this complex can accelerate its function of induce tumor cell apoptosis. This discovery arosed the interest to investigate the physicochemical character and mechanism of this complex. But because the limit of instrument, there was no satisfactory production. This research used a new method—ESR to study the configuration of azurin, spinned the spin label 3-maleido-proxyl to the -SH- of azurin specifically, according to the change of τ_c in the spectrum of ESR to embody the alter of inner configuration of protein.Accordingly we hoped to find the unique superiority of this instrument to study the structure of protein complex. Then we can use this instrument to explore the mechanism and chemical character of the protein complex. The result proved that in different solvent the spin label has different τ_c. Along with the increase of glycerin gradient, the τ_cof spin label also increased. In the case of using guanidine HC1 denaturalize, with the increase of guanidine concentration, the τ_ c of spin label decreased, this indicate that the inner stereo-structure of protein has loosen, and the configuration has relax. We got the similar conclusion when used the denaturalization of heating, we denaturalized the protein in the range of 65°C to 85°C, via the study of ESR found when temperature increased τ_c decreased, the inner configuration of protein has loosed, copper broken away from protein center. From all these study we found electron spin label method can directly measure the microcosmic changes of protein in conventionality and abnormity condition, preceded to other apparatus, so it can explore the complex mechanism of complex protein.
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