Identification and Characterization of an Intermediate in the Thermal Unfolding Pathway of the Human Acidic Fibroblast Growth Factor
Han-min Wang, T. K. S. Kumar and Chin Yu
Department of Chemistry, National Tsing Hua University, Hsin Chu, Taiwan, R. O. C.
Human acidic fibroblast growth factor (hFGF-1) is a 154 amino acid, single polypeptide chain bereft of disulfide bonds. The secondary structural elements in the protein include twelve β-strands arranged in aβ-trefoil motif. We examined the thermal unfolding pathway of hFGF-1 under various pH conditions using fluorescence spectroscopy. The Tm value estimated from the thermal unfolding profiles of hFGF-1 obtained using fluorescence and far UV circular dichroism spectroscopy differed by at least 10℃. These results suggest that the temperature induced unfolding of hFGF-1 proceeds via the accumulation of intermediate(s). Thermal unfolding of hFGF-1 monitored by 1-anilino naphthalene sulfonate fluorescence revealed that the accumulated intermediate has structural features resembling the unfolded state. These results would be presented in greater detail.