Secreted Phosphoprotein 24 kD (Spp24) and Spp14 Affect TGF-β Induced Bone Formation Differently

doi:10.1371/journal.pone.0072645

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PLoS One. 2013; 8(8): e72645.

Published online 2013 Aug 26. doi: 10.1371/journal.pone.0072645

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Table 1

Kinetic parameters as determined by surface plasmon resonance for the interactions of TGF-β1, TGF-β2, and BMP-2 versus each of the four Spp24 isoforms.

		spp14.5	spp16.0	spp18.1	spp24
TGF-β1	k_a (M^-1 s^-1×10³)	4.18	5.55	10.00	71.9
	k_d (s^-1×10^-3)	5.89	12.2	10.6	3.93
	K_D (k_d//k_a) (μM)	*1.41*	*3.25*	*1.39*	*0.065*
TGF-β2	k_a (M^-1 s^-1×10³)	2.39	1.34	3.64	32.4
	k_d (s^-1×10^-3)	5.39	5.66	10.9	5.86
	K_D (k_d//k_a) (μM)	*3.22*	*4.24*	*3.18*	*0.194*
BMP-2	ka (M^-1 s^-1×10³)	15.3	63.6	263	311
	k_d (s^-1×10^-3)	3.60	2.61	1.26	5.50
	K_D (k_d//k_a) (μM)	*0.236*	*0.041*	*0.005*	*0.018*

k_a represents “recognition”, k_d represent “stability”, and K_D stand for the actual “affinity” of the proteins. The values pertaining to BMP-2 are from reference 16 and are shown for purposes of comparison.