Table 1. Characteristic Transmembrane Transport Parameters for COSANs^a as Molecular Carriers of Heptaarginine,^b Determined by CF Assay in EYPC Vesicles.

carrier	Ymax (%)c	EC50 (μM)d	Eae
PyBu	100	103	4.8
B12Br122–f	95	48 ± 4	6.1
1	100	3.2	12.1
2	100	2.3	12.8
3	100	0.9	14.7
4	100	1.9	13.2
5	98	2.8	12.1
6	100	0.9	14.6

^aCOSANs used as cesium salts, analogous experiments with the sodium salt of 1 confirmed that the counter cation does not affect significantly the transport activity (Figure S6 and Table S2).

^b1 μM Trp-Arg₇ for experiments with COSANs and PyBu; note that experiments at higher peptide concentration (20 μM), performed for COSAN 2, afforded comparable activity (Figure S7 and Table S3).

^cMaximal activity; ±5% error (SD).

^dEffective concentration to reach 50% activity of Y_max; 5% error (SD), unless stated differently.

^eActivator efficiency, E_a = Y_max (pEC₅₀)/f, where pEC₅₀ is the negative logarithm of EC₅₀ in mM, and f is a scaling factor, which is set as 20.6 to calibrate the highest (previously known) activator efficiency as 10;^75,76 10% error (SD, calculated by considering error propagation with respect to both, Y_max and EC₅₀).

^fTransport experiments with B₁₂Br₁₂^2– were conducted with the HPTS/DPX assay and 20 μM Trp-Arg₇.¹⁴