Table 1.
Rate constants and equilibrium dissociation constants (KD) of folic acid (FA), methotrexate (MTX), Ac-G5-(FA)8 (1), and Ac-G5-(MTX)5 (2c) to the folate binding protein measured by surface plasmon resonance spectroscopy.
| Ligands | FA | MTX | 1 | 2c |
|---|---|---|---|---|
| KD (M)a | 1.1(±0.50)×10−5 | 2.4(±0.11)×10−5 | 2.3(±0.35)×10−9 | 2.6(±1.0)×10−8 |
| kon (M−1s−1) | 1.1(±1.0)×103 | 7.0(±5.6)×102 | 2.9 (±2.2)×105 | 3.4(±2.5)×104 |
| koff (s−1) | 1.2(±0.2)×10−2 | 1.7(±0.6)×10−2 | 6.6 (±0.76)×10−4 | 8.7(±2.5)×10−4 |
| βb | 1 | 1 | 4820 (588c) | 923 (185c) |
a
Each dissociation constant (KD = koff/kon) represents a mean value calculated by averaging the data obtained from at least three sets of measurement per injection concentration;
b
β = multivalent binding enhancement = [KDmono ÷ KDmulti];
c
valency (n)-corrected value = [β ÷ n] where n is equal to either 8.2 (1) or 5.0 (2c).