Cyclo(-RGDfK) TFA

The constant of affinity (K_D) of Cyclo (-RGDfK-) for purified integrin is 41.70 nM.^[2] Cyclo (-RGDfK) is reacting with HEK293(β3) cells moderately.^[3] Cyclo(-RGDfK-) modified micelles shows strong affinity to T-24 cells and strong inhibitory effect on the proliferation of T-24 cells.^[4]

In athymic mice bearing α(v)β(3)-integrin-positive C6 gliomas, Cyclo (-RGDfK-) modification induces less tumor progression, less tumor metabolic activity, fewer intratumoral vessels.^[5]

• Isolated Integrin Binding Assays.

  Purified integrin (1 μg/mL; 4℃) is used to coat 96-well microtitre plates, which are then blocked with bovine serum albumin (BSA) (3% in 1 mM CaCl_{2, 1 mM MgCl2,10 pM MnCl2, 100 mM NaC1,50 mM trishydroxymethyl-aminomethane; pH 7.4), and incubated (3 h at 30 ℃) with biotinylated ligands (1 pg/mL in binding buffer: 0.1% BSA, 1 mM CaCl2,1 mM MgCl2, 10 μM MnCl2, 100 mM NaCl, 50 mM trishydroxymethyl-aminomethane; pH 7.4) in the presence or absence of serially diluted peptides. After washing (3×5 min with binding buffer), bound biotinylated ligand is detected with alkaline-phosphatase conjugated goat antibiotin antibodies (1 μg/mL; 1 h, 37℃), using p-nitrophenyl phosphate as chromogen. Cyclo (-RGDfK) binding in the absence of competitor is defined as 100% signal; binding to blocked wells in the absence of integrin is defined as 0%. Concentrations of Cyclo (-RGDfK) required for 50% inhibition of signal (IC50 values) are estimated graphically.}