TAILIEUCHUNG - Báo cáo Y học: Protein methylation as a marker of aspartate damage in glucose-6-phosphate dehydrogenase-deficient erythrocytes

The ÔMediterraneanÕ variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency is due to the C563CT point mutation, leading to replacement of Ser with Phe at position 188, resulting in acute haemolysis triggered by oxidants. Previous work has shown increased formation of altered aspartate residues in membrane proteins during cell ageing and in response to oxidative stress in normal erythrocytes. These abnormal residues are specifically recognized by the repair enzyme L-isoaspartate (D-aspartate) protein O-methyltransferase (PCMT; EC ). . | Eur. J. Biochem. 269 2032-2039 2002 FEBS 2002 doi Protein methylation as a marker of aspartate damage in glucose-6-phosphate dehydrogenase-deficient erythrocytes Role of oxidative stress Diego Ingrosso1 2 Amelia Cimmino1 Stefania D Angelo1 Fiorella Alfinito3 Vincenzo Zappia1 2 and Patrizia Galletti1 2 1 Department of Biochemistry and Biophysics School of Medicine Second University of Naples Italy 2Cardiovascular Research Centre School of Medicine Second University of Naples Italy 3Department of Hematology School of Medicine University of Naples Federico II Italy The Mediterranean variant of glucose-6-phosphate dehydrogenase G6PD deficiency is due to the C563CT point mutation leading to replacement of Ser with Phe at position 188 resulting in acute haemolysis triggered by oxidants. Previous work has shown increased formation of altered aspartate residues in membrane proteins during cell ageing and in response to oxidative stress in normal erythrocytes. These abnormal residues are specifically recognized by the repair enzyme L-isoaspartate D-aspartate protein O-methyltransferase PCMT EC . The aim of this work was to study the possible involvement of protein aspartate damage in the mechanism linking the G6PD defect and erythrocyte injury through oxidative stress. Patients affected by G6PD deficiency Mediterranean variant were selected. In situ methylation assays were performed by incubating intact erythrocytes in the presence of methyl-labelled methionine. Altered aspartate residues were detected in membrane proteins by methyl ester quantification. We present here evidence that in G6PD-deficient erythrocytes damaged residues are significantly increased in membrane proteins in parallel with the decay of pyruvate kinase activity used as a cell age marker. Erythrocytes from patients were subjected to oxidative stress in vitro by treatment with t-butylhydroperoxide monitored by a rise in concentration of both methaemoglobin and .

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