ИСТИНА

Glycation of proteins is of great importance, because this process is accelerated with increase in blood glucose level in patients with diabetes. We investigated the effect of glycation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) on the catalytic properties and stability of the enzyme. The enzyme was glycated by glucose or glyceraldehyde-3-phosphate (G-3-P). The efficiency of the glycation was estimated by the rate of the formation of fructosamines. The enzymatic activity of GAPDH decreased by 90% and 50% after 24 h of incubation in the presence of G-3-P and glucose, respectively. The addition of low-molecular weight thiols partially defended the enzyme from inactivation. The glycation decreased thermal stability of GAPDH and increased its propensity to aggregation. Thus, it was demonstrated that the substrate of the reaction catalyzed by GAPDH inactivates the enzyme, and promote its denaturation and aggregation. We suppose that glycation of GAPDH may be an important regulatory mechanism controlling the rate of ATP-producing stages of glycolysis. Besides, considering the involvement of GAPDH in the induction and development of neurodegenerative diseases, the modification of this protein by sugars and aldehydes may affect its ability to produce amyloid structures with different amyloidogenic proteins. The work was supported by Russian Scientific Foundation grant 16-14-10027.