Studies of amino acid content and transport in glutathione-deficient erythrocytes from a patient with pyroglutamic acidemia (5-Oxoprolinemia)

Repeated biochemical studies of the erythrocytes of a patient with pyroglutamic acidemia have shown a varying biochemical disorder in these cells. Whereas earlier studies demonstrated absence of glutathione and massive amino acid loading in erythrocytes, these cells later contained small but readily measurable amounts of glutathione and had a relatively normal amino acid content. The marked increase in amino acids after acid hydrolysis of erythrocytes had also disappeared. Transport studies showed a significant increase in the active transport of glycine, while the transport of other amino acids was comparable to that of normal cells. We were unable to detect any activity of γ-glutamyl transpeptidase in human erythrocytes. Our observations suggest a role for glutathione in the transport of amino acids by erythrocytes, but at present no definite conclusion can be drawn with regard to the participation of the γ-glutamyl cycle in this process. The biochemical variability in our patient's erythrocytes is unexplained and should be searched for in other patients with pyroglutamic acidemia.