CONFORMATIONAL HETEROGENEITY OF APOAZURIN MUTANT M121L FROM Pseudomonas aeruginosa:A FLUORESCENCE STUDY
荧光研究表明去辅基天青蛋白突变体M121L至少存在两种不同的构象

Unfolding of Pseudomonas aeruginosa apoazurin has been suggested to be more complex than the Zn2+ substituted form. This complexity was investigated using a mutant M121L with urea as denaturant. Although the equilibrium unfolding/refolding showed a two-state transition, its kinetic behaviour was complex and could be best understood as two interconvertible conformations coexisting in solution. One conformation (N1), which was unfolded fast, was found to be refolded independently through a three-state mechanism with a fast-populated intermediate on its pathway, while refolding of the other (N2), which was unfolded slow, was dominantly through N1 folding pathway, then to be isomerised into N2. Adding of the extraneous ligand Zn2+ could integrate these two native conformations into a unique complex and the corresponding unfolding kinetics was reduced to a monophasic process. This provides new insight on the unfolding behaviour of this protein.