The most important clinical marker for glycemic index is HbA1c, glycated haemoglobin, which is basically a posttranslational modification of haemoglobin with glucose. The permeable nature of the erythrocyte membrane with respect to glucose allows the molecule to react with the most abundant candidate molecule in erythrocyte which is haemoglobin. There are many proteins present with haemoglobin in erythrocytes. Once glucose becomes accessible to them, similar posttranslational modifications like HbA1c are expected to exist in the erythrocyte proteome. Hence, the fundamental question we are asking in this project is besides haemoglobin, which are the other candidates getting glycated simultaneously. In this project, we are trying to profile those proteins using a mass spectrometry based proteomics platform.
Similar to glycation, glutathionylation is also an example of posttranslational modification. The glutathionyl haemoglobin has been reported to act as a marker for oxidative stress under many medical conditions. Under the condition of oxidative stress, the abundant antioxidant in erythrocyte, glutathione, modifies free accessible cysteine on haemoglobin. As the reaction is specific to the thionyl functional group (SH), it is expected that other protein molecules in the erythrocyte might undergo glutathionylation as well. Here, we are trying to profile glutathionylation of erythrocyte proteins using a proteomics platform.