Table 2. Double functions of HWTX-XI and its mutants.

Protein	to trypsin			to Kv1.1
	N	Kd [M]	ΔH [kcal/mol]	IC50 (mM)
wt	1.07	2.3×10−10	−8.94	2.57
aBPTI	1.17	6.57×10−9	−6.17	136
bDTX-K	–	–	–	0.01
R10T	0.92	6.58×10−11	−12.5	2.49
R12P	1.14	4.15×10−10	−7.36	2.61
K14N	0.9	1.95×10−6	−2.41	2.66
K14A	–	–	–	2.61
S16R	1.1	2.77×10−10	−7.83	2.53
G36R	1.12	9.7×10−10	−8.35	2.55
D2K	1.02	2.4×10−10	−8.81	0.65
T3L	1.04	2.35×10−10	−8.79	3.42
T3Y	1.05	2.2×10−10	−8.83	3.15
R5I	1.01	2.3×10−10	−8.78	36.5
L6A	1.03	2.3×10−10	−8.69	500
L6Y	0.98	2.3×10−10	−8.88	481
G24W	1.06	2.2×10−10	−8.87	2.81
G24Q	1.02	2.5×10−10	−8.92	3.07
R25A	1.01	2.4×10−10	−8.76	10.8
K50A	1.05	2.3×10−10	−8.94	4.62
cAAKY-	1.05	2.4×10−10	−8.99	0.53
dPR-	1.02	2.3×10−10	−8.9	2.46

The binding parameters of HWTX-XI and its mutants to trypsin were measured by Isother Titration Calormetry. The experiments were performed in 20 mM HEPES, pH 7.5, at 25°C. Errors in N and ΔH values are ±10%, and in Kd values are ±30%. The IC₅₀ values of HWTX-XI and its mutants effect on Kv1.1 channels were carried out in X. laevis oocytes. Errors in IC₅₀ values are ±10%.

–, no effect detected. ^a a potent trypsin inhibitor purified from bovine pancreas [15]; ^b a potent blocker for Kv1.1 purified from the venom of Dendroaspis polylepis [25]; ^c substitute for 1-IDT-3 in HWTX-XI; ^d adding two residues ahead of the sequence of HWTX-XI.