Molten Globule State of Proteins-Conformation, Stability, and Its Physiological Role

点击翻译按钮获取中文摘要

The molten globule, state, a compact denatured state with significant secondary structure but a largely disordered tertiary structure, has been proposed to be a major intermediate state in protein folding and its participation in various in vivo processes has been suggested. However, much remains unknown-particularly the mechanism of conformational stability and its physiological role. We carried out the International Scientific Research Program in order to clarify these problems and obtained the following results.1)Conformation and stability of the molten globule state Structural characteristics of various conformational state of apomyoglobin were studied by solution X-ray scattering. The results show that the molten globule state is expanded from the native state and that it contains a core comprising a cluster of helices and flaring tails. Role of hydrophobic and electrostatic interactions in stabilizing the molten globule state of apomyogobin and cytochrome c was studied by calorim … More etry and circular dichroism. It was shown that the stability of the molten globule state is critically determined by a balance of charge repulsive forces and hydrophobic forces. By comparing the various conformational states, we constructed a folding profile, which shows that the protein becomes more compact with formation of the secondary structure. The profiles are consistent with the prediction on the basis of the statistical mechanical theory.2.Nature of substrate proteins recognized by molecular chaperons Mechanism of interaction of GroEL and substrate proteins was studied. We found that GroEL recognizes the flexible and exposed hydrophobic clusters of the substrate proteins. On the other hand, DanK was found to recognize more disordered conformational states.3.Analysis of the molten globule state by mass spectrometryH/D exchange reaction of the molten globule state was analyzed by electrospray mass spectrometry. It was indicated that mass spectrometry is useful to characterize the structural flexibility of the molten globule state. Less