A STUDY ON IN-VITRO GLYCATION PROCESSES BY MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY

The number of glucose molecules condensed on glycated bovine serum alb umin have been easily determined by means of matrix-assisted laser des orption/ ionization mass spectrometry. Measurements were carried out o n samples from incubation of the protein with glucose at different con centrations (0.02 M, 0.2 M, 2 M and 5 M). A clear increase in molecula r mass of BSA with respect to incubation time is detected. In contrast to what is observed with fluorescence, the plots of molecular mass in crease vs. incubation time show the occurrence of a steady state, corr esponding to the complete saturation of all the protein sites reactive against glucose. Comparison of fluorescence and molecular mass data r eveals that some further reactions, different from condensation, must take place, which could be in principle either intramolecular or origi nated by reactivity of modified condensed glucose moieties vs. free gl ucose.