Abstract
MR deficiency is the first inborn error of folate metabolism to be studied in cultured fibroblasts. Cells from patients with this disorder have between 14 and 20% of the normal enzyme activity. Because deficient fibroblasts fail to grow in a culture medium in which homocysteine replaces methionine, it was presumed that they lack methyl-HH4PteGlu, the product of MR and the methyl donor for the conversion of homocysteine to methionine. Folate concentration measured by Lactobacillus casei was not different in normal cells and in mutants, nor was the concentration of Pedio-coccus cerevisiae-active and Streptococcus faecalis-active folate in the cells. The deficient cells contained significantly less methyl -H4PteGlu than did controls as determined by the ratio of P. cerevisiae or S. faecalis-active material to L. casei-active material. Analysis of folate levels before and after treatment with folate-depleted human serum reveals that in both normal and mutant cell lines most of the folate exists as folate polyglutamates.
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Rosenblatt, D., Cooper, B., Lue-Shing, S. et al. FOLATE COENZYMES IN METHYLENE-H4PTEGLU REDUCTASE (MR) DEFICIENT FIBROBLASTS. Pediatr Res 11, 463 (1977). https://doi.org/10.1203/00006450-197704000-00557
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DOI: https://doi.org/10.1203/00006450-197704000-00557