CRYSTAL-STRUCTURE OF BASIC FIBROBLAST GROWTH-FACTOR AT 1.6 A RESOLUTION

We have determined the crystal structures of two types of human basic fibroblast growth factor, the serine analogue and the wild-type, at 1.6 and 2.5 angstrom resolution, respectively. Two good heavy atom derivatives were found and used for multiple isomorphous replacement phasing. The atomic coordinates were refined using the Hendrickson & Konnert program for stereochemically restrained refinement against structure factors. The crystallographic R factors were reduced to 15.3% for the serine analogue structure and 16.0% for the wild-type structure. The serine analogue and wild-type structures have been found to be almost identical, the root-mean-square deviation between the corresponding C-alpha atoms being 0.11 angstrom. Their structures are composed of twelve beta-strands forming a barrel and three loops. Their molecules have an approximate threefold internal symmetry and are similar in architecture to that of interleukin-1-beta. A possible heparin-binding site, which comprises five basic residues, Lysll9, Argl20, Lysl25, Lysl29, and Lysl35, has been revealed by calculating the electrostatic potential energy.