Profiling of Methylglyoxal Blood Metabolism and Advanced Glycation End-Product Proteome Using a Chemical Probe

Methylglyoxal
(MG) is quantitatively the most important precursor
to advanced glycation end-products (AGEs), and evidence is accumulating
that it is also a causally linked to diabetes and aging related diseases.
Living systems primarily reside on the glyoxalase system to detoxify
MG into benign d-lactate. The flux to either glycation or
detoxification, accordingly, is a key parameter for how well a system
handles the ubiquitous glyoxal burden. Furthermore, insight into proteins
and in particular their individual modification sites are central
to understanding the involvement of MG and AGE in diabetes and aging
related diseases. Here, we present a simple method to simultaneously
monitor the flux of MG both to d-lactate and to protein AGE
formation in a biological sample by employing an alkyne-labeled methylglyoxal
probe. We apply the method to blood and plasma to demonstrate the
impact of blood cell glyoxalase activity on plasma protein AGE formation.
We move on to isolate proteins modified by the MG probe and accordingly
can present the first general inventory of more than 100 proteins
and 300 binding sites of the methylglyoxal probe on plasma as well
as erythrocytic proteins. Some of the data could be validated against
a number of in vivo and in vitro targets for advanced glycation previously known from the literature;
the majority of proteins and specific sites however were previously
unknown and may guide future research into MG and AGE to elucidate
how these are functionally linked to diabetic disease and aging.