Affinity (pKB) and functional cooperativity with ACh (logαβACh) estimates of the basic peptides, PLA, protamine, and MBP
Values represent the mean ± S.E. from at least three experiments performed in duplicate.
| WT | N410K+T423K | |||||
|---|---|---|---|---|---|---|
| pKBa | LogαβAChb | nc | pKB | LogαβACh | n | |
| PLA | 7.00 ± 0.05 | −3# | 3 | 6.41 ± 0.25* | −0.70 ± 0.56* | 3 |
| MBP | 6.54 ± 0.29 | −3# | 4 | n.a. | n.a. | 4 |
| Protamine | 6.01 ± 0.25 | −0.86 ± 0.19 | 4 | n.a. | n.a. | 4 |
n.a., not applicable, as no alteration of the EC50 of ACh was observed, and therefore, no estimate could be provided.
↵a Negative logarithm of the allosteric modulator equilibrium dissociation constant.
↵b Logarithm of the cooperativity factor for the interaction between the peptides and ACh.
↵c Number of experiments performed.
↵* Significantly different from the corresponding value at the wild type (P < 0.05), Student’s t test.
↵# Interaction was indistinguishable from competition (F-test), indicative of very high negative cooperativity (αβ → 0), and thus the cooperativity factor was constrained to an arbitrarily low value.