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Glycation of Liver Cystatin: Implication on its Structure and Function.
Mir Faisal Mustafa1, Bilqees Bano2
1Department of Biochemistry, Faculty of Life Sciences, A.M.U., Aligarh, U.P, 202002, India.
Journal of Fluorescence
|June 29, 2016
Summary
Diabetic conditions increase sugars that damage proteins like liver cystatin. Glycation alters liver cystatin structure and function, potentially causing liver damage and cirrhosis.
Area of Science:
- Biochemistry
- Molecular Biology
- Diabetic Complications
Background:
- Elevated reducing sugars in diabetes cause protein glycation, leading to loss of protein structure and function.
- Protein glycation contributes to cell damage and the formation of advanced glycation end products (AGEs).
Purpose of the Study:
- To investigate the impact of glycation by different reducing sugars (glucose, fructose, ribose) on liver cystatin (BLC).
- To assess the functional consequences of sugar-induced glycation on liver cystatin's enzymatic activity.
Main Methods:
- Purification of liver cystatin (BLC) using affinity chromatography.
- Incubation of BLC with glucose, fructose, and ribose.
- Monitoring glycation adduct formation using UV-Vis absorption and AGE-specific fluorescence spectroscopy.
- Analyzing conformational changes via intrinsic fluorescence and far-UV circular dichroism (CD) spectroscopy.
- Assessing the effect of glycated BLC on papain activity using a caseinolytic assay.
Main Results:
- Glycation with D-ribose, fructose, and glucose induced significant conformational changes in BLC, altering its structure.
- D-ribose caused the most rapid misfolding of BLC into an intermediate state with reduced alpha-helical content compared to fructose and glucose.
- Glycation decreased the activity of papain in the presence of glycated liver cystatin, with ribose having the most pronounced effect.
- Spectroscopic analysis confirmed BLC modification and AGE formation.
Conclusions:
- Reducing sugars, particularly ribose, significantly alter the structure and function of liver cystatin.
- Glycation of liver cystatin may disrupt the liver cystatin-cathepsin balance in diabetes.
- This imbalance could contribute to impaired proteinase activity, potentially leading to liver damage and cirrhosis.
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