Glycation profile of minor abundant erythrocyte proteome across varying glycemic index in diabetes mellitus.

PURPOSE

Long-term glycemic index in patients with diabetes mellitus (DM) is measured by glycated hemoglobin (HbA) besides blood glucose. In DM, the primary amino groups of proteins get glycated via non-enzymatic post-translational modification. This study aims at identifying and characterizing site-specific glycation of erythrocyte proteome across varying glycemic index in patients with DM.

EXPERIMENTS

We isolated the glycated erythrocyte proteome devoid of hemoglobin from control and diabetic samples using boronate affinity chromatography. Proteomic analysis was performed using nanoLC/ESI-MS proteomics platform. The site-specific modification on different proteins was deciphered using a customized database.

RESULTS

We report 37 glycated proteins identified and characterized from samples with HbA of 6%, 8%, 12%, and 16%. Our results show that both extent and site-specific modification of proteins increased with increasing HbA. The observed residue-specific modifications of catalase, peroxiredoxin, carbonic anhydrase, lactate dehydrogenase B and delta-aminolevulinic acid dehydratase were correlated with the literature report on their functional disorder in DM.

CONCLUSIONS

and clinical relevance: 37 glycated erythrocyte proteins apart from hemoglobin were characterized from DM patient samples with varying HbA values. We correlated the site-specific glycation and associated functional disorder of five representative proteins. However, the clinical correlation with the observed modifications needs further investigation.