Mechanism of Unfolding of Goat Lung Cystatin During Urea and Guanidine Hydrochloride Induced Denaturation |
| |
Authors: | Mohd Shahnawaz Khan Bilqees Bano |
| |
Institution: | (1) Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, UP, 202002, India |
| |
Abstract: | Cystatins essentially regulate lysosomal cysteine protease besides affecting several physiological processes. In the present
study, denaturation of a high molecular weight cystatin (Mr 66.4 kDa) purified from goat lung (GLC-I) has been studied by
monitoring its inhibitory activity, intrinsic fluorescence, circular dichroism (CD), and binding of ANS. It was found that
increasing concentration of GdnHCl significantly enhances the inactivation and unfolding of the purified inhibitor (GLC-I)
with complete loss of inhibitory activity at 4 M GdnHCl. Denaturation of GLC-I in the presence of GdnHCl is accompanied by
red shift (15 nm) of the emission maximum as shown by intrinsic fluorescence. The inhibitory activity of GLC-I was increased
by 1.5 fold at 2 M urea; however, it decreased with further increased of the urea concentration. Intrinsic fluorescence studies
of GLC-I in the presence of 0–3 M urea shows blue shift of 5 nm, suggesting stabilization of the inhibitor followed by 5 nm
red shift at higher concentration. ANS binding studies in the presence of urea indicate significant changes in the tertiary
structure of the inhibitor. Thus, our result shows denaturation profile of GLC-I following simple two state transitions in
the presence of GdnHCl while it proceeds through an intermediate state in the presence of urea. |
| |
Keywords: | ANS binding Circular dichroism Enzyme inhibitor Fluorescence Goat lung cystatin |
本文献已被 SpringerLink 等数据库收录! |
|