Table 1. The apparent association (k_a), dissociation (k_d) rate constants and equilibrium dissociation constants (K_D) for the interaction of BMP4 and Wnt3a with immobilized heparin or CS-E.

Ligand	GAG	ka (M−1Sec−1)	kd (Sec−1)	KD (nM)
BMP4	Heparin	2.76×105	1.92×10−2	69.4
BMP4	CS-E	1.44×105	4.33×10−3	30.0
Wnt3a	Heparin	2.22×105 a	5.77×10−3 a	26.0 a
Wnt3a	CS-E	8.26×105	2.26×10−2	27.3

The k_a, k_d and K_D values were determined by SPR analysis.

^aThe k_a, k_d and K_D values of Wnt3a against heparin have been published in our previous paper [17].