RESUMO
Cord blood samples from ten term infants were fractionated into populations of young and old erythrocytes and compared with cells prepared in a similar fashion from eight normal adults. The old cell fraction from the newborn infants had very low phosphofructokinase activity and did not display the usual decline of activity of the enzymes phosphoglycerate kinase and enolase. In addition, the old cells from the newborn infants demonstrated impaired glucose consumption, which, upon analysis of the pattern of glycolytic intermediates, appeared to be a result of the phosphofructokinase deficiency. These findings suggest that cells produced earlier in gestation possess the developmental characteristics of fetal blood to a more significant degree and that these biochemical alterations may produce functional impairment.
Assuntos
Envelhecimento Eritrocítico , Eritrócitos/enzimologia , Recém-Nascido , Fosfofrutoquinase-1/sangue , Fosfoglicerato Quinase/sangue , Fosfopiruvato Hidratase/sangue , Adulto , Glicemia , Fracionamento Celular , Ensaios Enzimáticos Clínicos , Sangue Fetal/enzimologia , Glicóis/sangue , Hexoquinase/sangue , Humanos , Técnicas In Vitro , Fosfofrutoquinase-1/deficiênciaRESUMO
Studies of a Mexican kindred present evidence for a unique phenotype of erythrocyte glucosephosphate isomerase, GPI Valle Hermoso. The proband was apparently the homozygous recipient of a mutant autosomal allele governing production of an isozyme characterized by decreased activity, marked thermal instability, normal kinetics and pH optimum, and normal starch gel electrophoretic patterns. Unlike previously known cases, leukocyte and plasma GPI activities were unimpaired. This suggested that the structural alteration primarily induced enzyme instability without drastically curtailing catalytic effectiveness, thereby allowing compensation by cells capable of continued protein synthesis. Age-related losses of GPI, however, were not evident by density-gradient fractionation of affected erythrocytes.