Mechanisms of adenosine 5'-monophosphate catabolism in human erythrocytes
DE Paglia, WN Valentine, M Nakatani and RA Brockway
Uncertainties regarding the role of pyrimidine nucleotidase (PyrNase) in
AMP catabolism were resolved by studies of erythrocytes from normal
controls, controls with young mean cell ages, and patients with hereditary
hemolytic anemia due to severe deficiency of PyrNase. Hemolysates from the
latter exhibited undiminished capacity to dephosphorylate AMP over a broad
range of pH, indicating that PyrNase was not directly involved. In each
subject group, the rates of AMP dephosphorylation between pH 5.1 and 8.3
were indistinguishable from those of IMP, suggesting a potential role for
AMP-deaminase, an erythrocyte enzyme that was stimulated by coformycin at
pH 7.2. Quantitative analysis of catabolites in incubated hemolysates
confirmed that AMP degradation preferentially occurred via deamination to
IMP with subsequent dephosphorylation by another erythrocyte nucleotidase
isozyme, deoxyribonucleotidase. Both AMP-deaminase and
deoxyribonucleotidase have acidic pH optima with minimal activities at
physiologic pH, suggesting that this pathway of AMP catabolism could
accelerate depletion of the adenine nucleotide pool and thereby mediate the
demise of senescent erythrocytes sequestered in the spleen.
Volume 67,
Issue 4,
pp. 988-992,
04/01/1986
Copyright © 1986 by The American Society of Hematology
