Abstract
Summary: The specific activities of four folate enzymes have been measured in livers from preterm infants (Group 1), full-term infants (Group 2), and from control subjects (Group 3). The four enzymes studied were methylenetetrahydrofolate reductase (EC 1.1.1.68), methionine synthetase (EC 2.1.1.13), methylenetetrahydrofolate dehydrogenase (EC 1.5.1.5), and glutamate formiminotransferase (EC 2.1.2.5). The specific activities for methylenetetrahydrofolate reductase were 6.62 ± 0.51, 4.42 ± 0.31, and 2.60 ± 0.40 (nmoles formaldehyde/mg protein/h, mean ± S.E.) for groups 1, 2 and 3, respectively.
The specific activities for the three groups for methionine synthetase were 0.99 ± 0.11, 0.64 ± 0.06, and 0.42 ± 0.05 (nmoles methionine/mg protein/h, mean ± S.E.). The specific activities for the three groups for glutamate formiminotransferase were 84.1 ± 10.7, 108.6 ± 14.6, and 104.3 ± 17.8 (nmoles methenyltetrahydrofolate/mg protein/min, mean ± S.E.). The specific activities for the three groups for methylenetetrahydrofolate dehydrogenase were 0.16 ± 0.03, 0.39 ± 0.07, and 0.92 ± 0.16 (nmoles methenyltetrahydrofolate/mg protein/min, mean ± S.E.). During development, the specific activities of methylenetetrahydrofolate reductase and methionine synthetase decreased whereas the specific activity of methylenetetrahydrofolate dehydrogenase increased and that of glutamate formiminotransferase remained constant. In addition, the activities of methylenetetrahydrofolate reductase, methionine synthetase, and methylenetetrahydrofolate dehydrogenase were significantly influenced by postnatal age.
Speculation: Deficiency of two of the folate enzymes studied, methylenetetrahydrofolate reductase and glutamate formiminotransferase, are associated with genetic disorders. Knowledge of the developmental patterns of the folate enzymes in human liver may have important implications in the diagnosis and early treatment of these inborn errors of metabolism.
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Kalnitsky, A., Rosenblatt, D. & Zlotkin, S. Differences in Liver Folate Enzyme Patterns in Premature and Full Term Infants. Pediatr Res 16, 628–631 (1982). https://doi.org/10.1203/00006450-198208000-00008
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DOI: https://doi.org/10.1203/00006450-198208000-00008