Method for monitoring of the protein amino group changes during carbonylation.

ABSTRACT

OBJECTIVES: Carbonylation of the protein amino, guanidino and thiol groups is one of the important causes of vascular complications in diabetes. We developed a simple spectrophotometric method for monitoring of the changes in the protein amino group contents during carbonylation. DESIGN AND METHODS: The method is based on the reaction of amino group with p-benzoquinone in the slightly alkaline media. It was applied during carbonylation in vitro with methylglyoxal and in vivo in 13 patients with type 2 diabetes and 20 healthy persons. RESULTS: The method is simple, fast, precise (RSD in the range of 1.2-1.8%) and accurate (recovery about 100%). The content of amino groups in human serum albumin isolated from diabetics was significantly lower (p<0.01) in comparison with a control group. CONCLUSION: The method developed is suitable for quantification of protein amino groups during in vitro carbonylation as well as for clinical practice.