RESUMO
Fibrillation can be induced in proteins by altering solvent conditions. Stabilization of the protofibrillar structure arrests formation of longer fibers. Thermal stability and fibrillation of N-terminal domain of the hydrogenase maturation factor (HypF-N) were studied in the presence of a series of metal ions. Only Al(3+) was able to reverse the thermal denaturation of HypF-N upon heating. On being exposed to denaturing conditions, the native protein formed fibrillar structure under moderately denaturing conditions, whereas in the presence of Al(3+) , the protein was found to retain its native conformation. Under strongly denaturing conditions, only Al(3+) was able to stabilize the protein in the fibrillar state. Spectrofluorimetric analysis revealed that Al(3+) alone was able to stabilize the partially unfolded intermediate state of HypF-N. Based on the similarity in observations, we propose a link between reversal of thermal instability of HypF-N and its ability to form an intermediate structure in the presence of Al(3+) . Al(3+) stabilizes the partially unfolded state in the NâIâU equilibrium so that upon heating, the three-dimensional structure of the protein is not lost completely. Kinetic analysis confirmed that Al(3+) interacts with an early structure on the aggregation landscape and delays fibrillation. Under mildly denaturing state, HypF-N is able to recover its native conformation in the presence of Al(3+) and under strongly denaturing conditions, the protein does not acquire a completely disordered structure. Instead, it forms an ordered ß-sheet-rich structure.