Table 2.

Binding affinities of RGD-containing peptides to integrin receptors determined from the IC₅₀^*

RGD -containing peptide/sequence**	ανβ3	ανβ5	α5β1	αIIbβ3
1 c[RGDD(t-B uG)(M amb)]	3	2 0	4 2	2 40
2 c[(Mpa)RGDD(t-B uG)C]-N H2	2 0	2 10	3 90	7 0
3 G-c[(Pen)FRG DSFC]-A	2 70 0	4 6	1 80 0	3 40 0
4 G-c[(Pe n)R AR GD N PC]-A	5 2	3 30	2	3 0
5 Ac -c[(Pen)Y(Me)AR GD N(Tic)C]-N H2***	2	6	5	1 90
6 A cF-c[CR GD TFC]-N H2	1 4	8	2 60	1 25 0

^*IC₅₀ is the concentration (nM) at which 50% of the binding of ligand to integrin receptor is inhibited.

^**Abbreviations: Ac, Acetyl; t-BUG, tert-Butylglycine; Mamb, m-aminomethylbenzoic acid; Mpa, 3-Mercaptopropionic acid; Pen, Penicillamine; Tic, Tetrahydroisoquinoline-3-carboxylic acid; Y(Me), O-Methyltyrosine; AcF, acetylphenylalanine

^***Molecular structures of Ac-c[(Pen)Y(Me)ARGDN(Tic)C]-NH₂ (left) and its scrambled analog Ac-[(pen)RY(Me)AGND(Tic)C]-NH₂ (right) are: