The role of mass spectrometry in the study of non-enzymatic protein glycation in diabetes.

Mass spectrometry has been applied successfully to the study of non-enzymatic protein glycation, which is a topic of wide interest in the diabetes field. Low- and high-resolution mass spectra, GC/MS, and collisional activation spectroscopy allow the structural identification and quantitative evaluation of advanced glycation end-products, which represent important molecules for monitoring diabetes. More recently available techniques, such as ESI and MALDI/MS, have had a significant impact on analytical problems in diabetes. In particular, MALDI has been applied to the study of protein glycation in in vitro and in vivo conditions, because the number of glucose molecules that condense onto the protein can be easily determined by this approach. In the former case, glycation kinetics have been studied in various sugars and sugar concentrations, proteins, and buffer concentrations; in the latter, comparisons of MALDI spectra of circulating proteins from healthy and diabetic subjects determine the exposure of patients to high glucose levels. The method has been applied to an evaluation of the glycation level of immunoglobulins, and indicates that glycation takes place preferentially on the Fab fragment of the protein; data are relevant in relating immunological impairment with glycation-induced changes in the functionality of immunoglobulins.