Glycation of proteins as a source of superoxide.
For the monitoring of diabetes mellitus, the concentration of serum glycated proteins is currently measured by a colorimetric reaction using the dye nitroblue tetrazolium. As this reduction may depend on superoxide ions (O2-), we checked whether glycated proteins were capable of generating O2- in vitro. We incubated ferricytochrome c with glucose, fructose, 1-deoxy-1-morpholino-D-fructose (an analog of the 1-desoxy-1-amino-fructose radical found in glycated proteins) and glycated proteins prepared from diabetic blood serum. We found that these substances, except free glucose, were all able to generate O2- not only at alkaline pH, but even at pH 7.4 with a slower rate. The possibility of O2- formation from glycated proteins may explain some long term complications of diabetes mellitus.
Gillery
P
P
Laboratoire de Biochimie, Centre Hospitalier Universitaire, Hôpital Robert Debré, Reims, France.
Monboisse
J C
JC
Maquart
F X
FX
Borel
J P
JP
D001798:Blood Proteins / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism; D003920:Diabetes Mellitus / Q000097:blood*; D006442:Glycated Hemoglobin / Q000032:analysis*; D006023:Glycoproteins / Q000097:blood*; D006031:Glycosylation; D006801:Humans; D007202:Indicators and Reagents; D007700:Kinetics; D009580:Nitroblue Tetrazolium; D012016:Reference Values; D013481:Superoxides / Q000097:blood*
D001798:Blood Proteins; D003574:Cytochrome c Group; D006442:Glycated Hemoglobin; D006023:Glycoproteins; D007202:Indicators and Reagents; D009580:Nitroblue Tetrazolium; D013481:Superoxides