Structural Heterogeneity of Glycoform of Alpha-1 Acid Glycoprotein in Alcoholic Cirrhosis Patients
Altered glycosylation of serum proteins has been reported in different pathologic conditions. Changes in glycosylation of serum proteins in disease state have been extensively used for the development of noninvasive sensitive clinical tests for diagnostic purposes. The aim of the present research was to monitor the changes of glycoform of serum alpha1-acid glycoprotein (AGP) in alcoholic liver cirrhosis (ALC) patients which could be predicted as serological marker for diagnosis. AGP was isolated from the albumin depleted pooled sera of ALC patients as well as controls by monoclonal anti-AGP affinity column. The altered glycoforms of AGP was determined by HPLC mapping followed by mass spectrometry and GALAXY database search. N-glycans released from AGP by hydrazinolysis were labeled with 2-aminopyridine and separated by three successive HPLC columns, viz., DEAE, ODS and amide silica. Significant decrease of sialylation level was observed by HPLC in ALC patients group with respect to controls. The binding of SNA with AGP was found to be less in patients group than control by ELISA and lectin blotting using Sambucus nigra agglutinin (SNA). This variation of N-linked glycoforms and decreased level of sialic acid in AGP could be valuable for the diagnosis of ALC besides clinical examination and routine laboratory investigation that could be helpful for treatment strategy.
KeywordsAlpha-1-acid glycoprotein Glycosylation Alcoholic liver cirrhosis HPLC Sialic acid
List of Abbreviations
Alcoholic liver cirrhosis
Sambucus nigra agglutinin
The authors sincerely thank Prof. Y. K. Chawla, Department of Hepatology, Post Graduate Institute of Medical Education and Research, Chandigarh, India for providing patients’ sera. This study was supported in part by Grants from IMS for IMS visiting Professor from abroad and the Japan Society for the Promotion of Science (JSPS) Invitational Training Program for Advanced Japanese Research Institutes. BPC and GM gratefully acknowledge the research grant (52/22/2008-BMS) provided by the Indian Council of Medical Research, New Delhi.
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