Glyoxalase activity in human red blood cells fractioned by age

Human red blood cells were fractionated by density, which correlates with cell age, and the activities of glyoxalase I and glyoxalase II were determined for each fraction. The activity of glyoxalase I and glyoxalase II both significantly increased during maturation of the red blood cells (P less than 0.001), except in the most dense, old cell fraction where both glyoxalase activities decreased. The increase in glyoxalase activity from the reticulocyte-rich fraction to mature erythrocytes was substantial and markedly different from other glycolytic enzymes which typically decrease. This suggests that glyoxalase activity changes markedly during and probably after the maturation of reticulocytes to erythrocytes. The decrease in glyoxalase activity from the mature to old red blood cell fractions may be caused by oxidative inactivation of glyoxalases. The decreased capacity to metabolise methylglyoxal may be an important factor in red blood cell senesence. This is expected to be particularly important in diabetes mellitus where the rate of methylglyoxal formation is increased during hyperglycaemia.