Single heparin chains can bind multiple proteins  and likewise oligopeptide components of tissue scaffolds. It is not known whether oligopeptide binding can interfere with cognate protein binding. We examined a well-defined ternary system comprising fibroblast growth factor (aFGF), tetralysine (K4), with a heparin decamer (dp10) acting as non-covalent coupler. ESI-MS was uesd to assess binding affinities and complex stoichiometries as a function of ionic strength for dp10-K4 and for FGF-dp10. Electrostatic interactions for the former were evident from the decrease in binding above I = 40 mM;  stronger binding for aFGF-dp10 can be inferred from its greater salt resistance. Remarkably, dp10 can bind two FGF, but only one tetralysine. The limited binding of K4 to dp10 suggests that  tetralysine need not block growth factor binding; the 1:1:1 ternary complex is indeed observed. Salt resistance for aFGF-heparin>K4-heparin shows that the former binds more strongly. Compositional distributions of free and FGF-bound dp10 suggest that aFGF binding depends onheparin sulfation indicating a more nuanced approach than the use of heterogeneous native heparin for growth factor sequestration and release.

Using heparin to bind a growth factor to oligopeptide sequences via specific and nonspecific electrostatic interactions

246th National Meeting (2013)

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