Imaging and mapping heparin-binding sites on single fibronectin molecules with atomic force microscopy

TitleImaging and mapping heparin-binding sites on single fibronectin molecules with atomic force microscopy
Publication TypeJournal Article
Year of Publication2000
AuthorsLin H, Lal R, Clegg DO
Date Published2000 Mar 28
KeywordsAnimals, Binding Sites, Cattle, Dimerization, Disulfides, Fibronectins, Gold Colloid, Heparin, Image Enhancement, Microscopy, Atomic Force, Peptide Fragments, Peptide Mapping, Random Allocation, Serum Albumin

Fibronectin is composed of multiple homologous repeats and contains many functional domains. Two major heparin-binding domains have previously been identified: the Hep I site near the amino terminus and the Hep II site near the carboxyl terminus. The Hep II site has been considered the high-affinity heparin-binding site based on studies of fibronectin fragments. However, few studies have been carried out on heparin binding by intact fibronectin. We imaged single fibronectin molecules as well as heparin-coated gold particles bound to whole dimeric plasma fibronectin molecules with tapping mode atomic force microscopy. We observed heparin-gold particles preferentially bound at two locations that correspond to the Hep I and Hep II sites. Quantitative analysis of images of individual fibronectin-heparin-gold complexes showed that almost twice as many heparin-gold particles bound to the N-terminal Hep I site compared to the Hep II site. In contrast to previous findings with fibronectin fragments, these results suggest that the Hep I site has a binding affinity higher than or comparable to the Hep II site in the intact fibronectin molecule.

Alternate JournalBiochemistry
PubMed ID10727210
Grant ListEY066570 / EY / NEI NIH HHS / United States
EY09736 / EY / NEI NIH HHS / United States
GM056290 / GM / NIGMS NIH HHS / United States