Protein Research Chair, Department of Biochemistry, King Saud University, Riyadh, Kingdom of Saudi Arabia.
Environ Monit Assess. 2013 Oct;185(10):8005-10. doi: 10.1007/s10661-013-3150-2. Epub 2013 Mar 17.
Cystatins are thiol proteinase inhibitors ubiquitously present in the mammalian body. They serve a protective function to regulate the activities of endogenous proteinases, which may cause uncontrolled proteolysis and damage. In the present study, the effect of benzo(a)pyrene [BaP] on lung cystatin was studied to explore the hazardous effects of environmental pollutant on structural and functional integrity of the protein. The basic binding interaction was studied by UV-absorption, FT-IR, and fluorescence spectroscopy. The enhancement of total protein fluorescence with a red shift of 5 nm suggests structural scratch of lung cystatin by benzo(a)pyrene. Further, ANS binding studies reaffirm the unfolding of the thiol protease inhibitor (GLC-I) after treating with benzo(a)pyrene. The results of FT-IR spectroscopy reflect perturbation of the secondary conformation (alpha-helix to β-sheet) in goat lung cystatin on interaction with BaP. Finally, functional inactivation of cystatin on association with BaP was checked by its papain inhibitory activity. Benzo(a)pyrene (10 μM) caused complete inactivation of goat lung cystatin. Benzo(a)pyrene-induced loss of structure and function in the thiol protease inhibitor could provide a caution for lung injury caused by the pollutants and smokers.
组织蛋白酶抑制剂是广泛存在于哺乳动物体内的巯基蛋白酶抑制剂。它们具有保护功能，可以调节内源性蛋白酶的活性，否则这些蛋白酶可能会引起不受控制的蛋白水解和损伤。本研究旨在探讨环境污染物对蛋白质结构和功能完整性的危害作用，研究了苯并（a）芘对肺组织蛋白酶抑制剂的影响。通过紫外吸收、傅里叶变换红外光谱和荧光光谱研究了基本的结合相互作用。总蛋白荧光的增强伴随着 5nm 的红移，表明苯并（a）芘对肺组织蛋白酶抑制剂造成了结构损伤。此外，ANS 结合研究进一步证实，在苯并（a）芘处理后，巯基蛋白酶抑制剂（GLC-I）发生了展开。傅里叶变换红外光谱的结果反映了在与 BaP 相互作用时，山羊肺组织蛋白酶抑制剂二级构象（α-螺旋向β-折叠）的扰动。最后，通过其对木瓜蛋白酶的抑制活性检查了与 BaP 结合时胱抑素的功能失活。苯并（a）芘（10μM）导致山羊肺组织蛋白酶抑制剂完全失活。苯并（a）芘诱导的巯基蛋白酶抑制剂的结构和功能丧失可能为污染物和吸烟者引起的肺损伤提供警示。
