Tomova S, Cutruzzolà F, Barra D, Amiconi G, Ascenzi P, Djinović Carugo K, Menegatti E, Sarti P, Schnebli H P, Bolognesi M
Department of Biochemical Sciences, Alessandro Rossi Fanelli, University of Rome La Sapienza, Rome, Italy.
J Mol Recognit. 1994 Mar;7(1):31-7. doi: 10.1002/jmr.300070105.
Binding of the human recombinant secretory leukocyte proteinase inhibitor (SLPI) [native and with the methionyl residues at positions 73, 82, 94 and 96 of domain 2 oxidized to the sulfoxide derivative (Met(O) SLPI)] to bovine alpha-chymotrypsin (alpha-chymotrypsin) [native and with the Met192 residue converted to the sulfoxide derivative (Met(O) alpha-chymotrypsin)] as well as to native bovine beta-trypsin (beta-trypsin), which does not contain methionyl residues, has been investigated between pH 4.0 and 8.0, and between 10.0 degrees C and 30.0 degrees C, from thermodynamic and/or kinetic viewpoints. By increasing the number of oxidized methionyl residues present at the proteinase:inhibitor contact interface (from 0 to 3), the adducts investigated are increasingly destabilized and the relaxation time of the complexes into conformers less stable is enhanced. On the other hand, the selective oxidation of methionyl residues of SLPI and alpha-chymotrypsin, by reaction with chloramine T, does not affect the proteinase inhibition recognition mechanism. Therefore, even though conformational changes may occur in the conversion of native SLPI and native alpha-chymotrypsin to their Met(O) derivatives, a localized steric hindrance can be considered as the main structural determinant accounting for the reported results.
从热力学和/或动力学角度，研究了人重组分泌型白细胞蛋白酶抑制剂（SLPI）[天然型以及结构域2中第73、82、94和96位的甲硫氨酸残基被氧化为亚砜衍生物（Met(O) SLPI）]与牛α-胰凝乳蛋白酶（α-胰凝乳蛋白酶）[天然型以及Met192残基被转化为亚砜衍生物（Met(O) α-胰凝乳蛋白酶）]以及不含甲硫氨酸残基的天然牛β-胰蛋白酶（β-胰蛋白酶）在pH 4.0至8.0以及10.0℃至30.0℃之间的结合情况。通过增加蛋白酶 - 抑制剂接触界面处存在的氧化甲硫氨酸残基数量（从0增加到3），所研究的加合物越来越不稳定，复合物向稳定性较低的构象体的弛豫时间增加。另一方面，通过与氯胺T反应对SLPI和α-胰凝乳蛋白酶的甲硫氨酸残基进行选择性氧化，并不影响蛋白酶抑制识别机制。因此，尽管天然SLPI和天然α-胰凝乳蛋白酶转化为其Met(O)衍生物时可能会发生构象变化，但局部空间位阻可被视为解释所报道结果的主要结构决定因素。
