Stability studies on derivatives of the bovine pancreatic trypsin inhibitor.
Stability studies on derivatives of the bovine pancreatic trypsin inhibitor.
复制标题
牛胰蛋白酶抑制剂衍生物的稳定性研究。
作者：
H. Schwarz;H. Hinz;A. Mehlich;H. Tschesche;H. Wenzel
测定了牛胰蛋白酶抑制剂（BPTI）的两种选择性修饰类似物的吉布斯能、焓和熵数据，以提供表征（a）14-38二硫键的能量和熵贡献和（B）由在14和38位引入两个负电荷引起的总体稳定性变化的热力学参数的无模型集。研究的两种BPTI类似物是具有Cys-14和Cys-38羧甲基化的BPTI（BPTI-RCOM）和具有Cys-14和Cys-38羧酰胺甲基化的BPTI（BPTI-RCAM）。它们通过还原从天然BPTI获得，然后分别用碘乙酸或碘乙酰胺修饰巯基。在没有第三个二硫键的情况下，BPTI的所有热力学参数的温度依赖性急剧改变。即使在位置14和38的两个可解离的羧基而不是不带电荷的酰胺基团的明显微小的差异对稳定化焓的温度依赖性具有令人惊讶的大的影响。当14-38二硫键断裂时，BPTI在pH 2，25 ℃下的吉布斯能降低约70%。在所研究的整个pH范围内，BPTI-RCOM比BPTI-RCAM稳定。在pH 2，25 ℃下的-4kJ/mol的差异在pH 5，25 ℃下降低到-2.7kJ/mol。这一发现表明，两个负电荷的存在略微降低了BPTI-RCOM的较高稳定性;然而，两个电荷的总体效果仍然是稳定的。（250字处删节）
Gibbs energy, enthalpy, and entropy data were determined for two selectively modified analogues of bovine pancreatic trypsin inhibitor (BPTI) to provide a model free set of thermodynamic parameters that characterize (a) the energetic and entropic contributions of the 14-38 disulfide bridge and (b) the variation of the overall stability resulting from the introduction of two negative charges into the positions 14 and 38. The two BPTI analogues studied were BPTI having Cys-14 and Cys-38 carboxymethylated (BPTI-RCOM) and BPTI having Cys-14 and Cys-38 carboxamidomethylated (BPTI-RCAM). They were obtained from native BPTI by reduction, followed by modification of the sulfhydryl groups with iodoacetic acid or iodoacetamide, respectively. The temperature dependence of all thermodynamic parameters of BPTI is drastically altered in the absence of the third disulfide bridge. Even the apparently minute difference of two dissociable carboxyl groups instead of uncharged amide groups in positions 14 and 38 has surprisingly large effects on the temperature dependence of the stabilization enthalpy. The Gibbs energy of BPTI at pH 2, 25 degrees C, decreases by approximately 70% when the 14-38 disulfide bond is cleaved. BPTI-RCOM is more stable than BPTI-RCAM in the whole pH range studied. The difference of -4 kJ/mol at pH 2, 25 degrees C, is reduced to -2.7 kJ/mol at pH 5, 25 degrees C. This finding demonstrates that the presence of two negative charges reduces the higher stability of BPTI-RCOM slightly; however, the overall effect of the two charges is still a stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)
影响因子：
2.9
作者：
K. Chou;G. Némethy;M. Pottle;H. Scheraga
通讯作者：
K. Chou;G. Némethy;M. Pottle;H. Scheraga