Abstract
In this study, the stability and folding of Acidic Fibroblast Growth Factor (nFGF-1) is described. nFGF-1 is a ~15kDa, all beta-barrel protein which play key roles in several important cellular processes related to morphogenesis, development and angiogenesis. The conformational stability of the nFGF-1 have been determined by urea denaturation and thermal denaturation using fluorescence and far-UV CD (Circular Dichroism) spectroscopy. To investigate the internal motions, hydrogen-deuterium exchange experiments in the absence and presence of Sucrose Octa Sulfate(SOS) were performed. In contrast to the equilibrium unfolding monitored by optical probes, native like state H/D exchange data shows that the betatrefoil architecture of nFGF-1 does not behave as a single cooperative unit. This work also proves the conformational statues required for nFGF- 1 for its cell proliferation activity. nFGF-1 undergoes reversible unfolding. However, the reversibility of the unfolding reaction is formed to be dependent on the time of incubation of the protein in the denaturant. Prolonged incubation of the protein in the denaturant renders the protein incompetent to refold back to its native conformation. This phenomenon is observed to be independent of the nature of the denaturants used. In addition, the irreversibility of the unfolding process is not found to be associated with intermolecular disulfide bond formation or chemical modification induced by the denaturants. The refolding fatigue exhibited by the protein is observed to be relieved in the presence of molecular chaperonins such as GroEL. These results would be elaborately discussed.