Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, São Bernardo do Campo, São Paulo, Brazil.
Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo, Brazil.
Biochimie. 2021 Feb;181:226-233. doi: 10.1016/j.biochi.2020.12.014. Epub 2020 Dec 24.
rBmTI-A is a recombinant serine protease inhibitor that belongs to the Kunitz-BPTI family and that was cloned from Rhipicephalus microplus tick. rBmTI-A has inhibitory activities on bovine trypsin, human plasma kallikrein, human neutrophil elastase and plasmin with dissociation constants in nM range. It is characterized by two inhibitory domains and each domain presents six cysteines that form three disulfide bonds, which contribute to the high stability of its structure. Previous studies suggest that serine protease inhibitor rBmTI-A has a protective potential against pulmonary emphysema in mice and anti-inflammatory potential. Besides that, rBmTI-A presented a potent inhibitory activity against in vitro vessel formation. In this study, the tertiary structure of rBmTI-A was modeled. The structure stabilization was evaluated by molecular dynamics analysis. Circular dichroism spectroscopy data corroborated the secondary structure found by the homology modelling. Also, in circular dichroism data it was shown a thermostability of rBmTI-A until approximately 70 °C, corroborated by inhibitory assays toward trypsin.
rBmTI-A 是一种重组丝氨酸蛋白酶抑制剂，属于 Kunitz-BPTI 家族，它是从 Rhipicephalus microplus 蜱中克隆出来的。rBmTI-A 对牛胰蛋白酶、人血浆激肽释放酶、人中性粒细胞弹性蛋白酶和纤溶酶具有抑制活性，解离常数在纳摩尔范围内。它的特点是有两个抑制结构域，每个结构域都有六个半胱氨酸，形成三个二硫键，这有助于其结构的高度稳定。先前的研究表明，丝氨酸蛋白酶抑制剂 rBmTI-A 对小鼠肺气肿和抗炎具有保护潜力。此外，rBmTI-A 对体外血管形成具有很强的抑制活性。在这项研究中，对 rBmTI-A 的三级结构进行了建模。通过分子动力学分析评估了结构稳定性。圆二色性光谱数据证实了同源建模发现的二级结构。此外，在圆二色性数据中，rBmTI-A 的热稳定性约为 70°C，这与对胰蛋白酶的抑制试验结果一致。
