Double functions of HWTX-XI and its mutants.

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.

本研究采用等温滴定量热法（Isothermal Titration Calorimetry）测定了虎纹捕鸟蛛毒素-XI (HWTX-XI) 及其突变体与胰蛋白酶的结合参数。实验在20 mM 4-羟乙基哌嗪乙磺酸 (HEPES) 缓冲液（pH 7.5）、25℃条件下开展。结合位点数目（N）与焓变（ΔH）的测定误差为±10%，解离常数（Kd）的测定误差为±30%。
针对Kv1.1通道的HWTX-XI及其突变体的半数抑制浓度（IC50）实验在非洲爪蟾 (Xenopus laevis) 卵母细胞中进行，IC50值的误差范围为±10%。
注：符号“–”表示未检测到相关活性。a：从牛胰腺中纯化得到的强效胰蛋白酶抑制剂[15]；b：从黑曼巴 (Dendroaspis polylepis) 毒液中分离得到的强效Kv1.1通道阻滞剂[25]；c：在HWTX-XI的序列中替换1-IDT-3位点；d：在HWTX-XI的序列前端额外添加两个氨基酸残基。