Structure/activity relationships in basic FGF.
Although the FGFs have been subject to extensive biological studies, only limited progress has been made so far in determining the critical elements of structure-activity relationships in the FGFs. Among the recognized structural elements with potential to affect the biological activity of FGFs are the cysteine residues, and the heparin- and receptor-binding domains. These features have been studied using a variety of experimental approaches, but the available data are inconclusive. For example, ambiguity regarding the presence of a disulfide structure in FGFs was not resolved until the availability of x-ray crystal structure data. Furthermore, the functionally important heparin- and receptor-binding domains have been poorly characterized, with some interpretations being controversial. In this report, we describe a novel fragment of basic FGF (bFGF) with high biological activity [Ser78,96-bFGF(70-153)]. This fragment was generated by pronase treatment of heparin-bound recombinant Glu3,5Ser78,96-bFGF mutant and is active in vitro at an ED50 of about 100 ng/ml. The structure of the fragment and the manner by which it was generated provide additional insight into important aspects of structure-activity relationships in FGFs. Specifically, we conclude that (a) the cysteines in our bFGF mutant do not form a disulfide bond, (b) the high-affinity heparin binding of bFGF critically depends on an intact 3-dimensional structure of the growth factor rather than on specific heparin-binding sequence domains, and (c) the bFGF sequence between residues 70 and 122 is important for high biological activity.
Seddon
A
A
Medical Research Division, American Cyanamid, Pearl River, New York 10965.
Decker
M
M
Müller
T
T
Armellino
D
D
Kovesdi
I
I
Gluzman
Y
Y
Böhlen
P
P
D001665:Binding Sites; D004220:Disulfides; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry* / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008934:Mitogens; D010446:Peptide Fragments / Q000737:chemistry; D011956:Receptors, Cell Surface / Q000378:metabolism; D017468:Receptors, Fibroblast Growth Factor; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship
D004220:Disulfides; D008934:Mitogens; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D017468:Receptors, Fibroblast Growth Factor; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D006493:Heparin