Effect of methionine, glycine and serine on serine hydroxymethyltransferase activity in rat glioma and human neuroblastoma cells

Randall Lee Kohl, J. R. Perez‐Polo, W. B. Quay

    Research output: Contribution to journalArticle

    18 Scopus citations

    Abstract

    Human neuroblastoma SK-N-SH-SY5Y (5Y) and rat glioma (C6) cells were cultured with supplemental methionine, glycine, or serine for 3 to 6 days. Serine hydroxymethyltransferase (SHMT: L-serine: tetrahydrofolate 5,10-hydroxymethyltransferase, EC 2.12.1) was assayed radiometrically in whole cell homogenates, crude supernatant fractions and crude particulate fractions. No significant changes in specific activity or cellular morphology were noted at methionine, glycine, or serine concentrations up to 16 mM. Serine concentrations of 20 and 40 mM led to significantly lower gliomal enzyme specific activities. This activity was unevenly distributed between soluble and particulate fractions, with 190 and 398 nmoles of HCHO formed per mg of protein per hour, respectively. Growth stage and time of incubation were major determinants of enzyme specific activity. C6 cells' specific activity rose slowly with increasing time in culture until cellular confluence. At this time there was a pronounced elevation in specific activity, occurring more rapidly in cells grown in 1.2 mM methionine. Intracellular amino acid analysis of C6 cells demonstrated a significant rise in methionine after 4 days in media containing 0.2 mM methionine. No appreciable diminution in the intracellular levels of glycine or serine occurred following incubation in excess methionine. It is concluded that SHMT-specific activity in C6 and 5Y cells is not regulated by glycine, serine, or methionine levels and that high concentrations of these amino acids (> 30 mM) are not detrimental to these cells derived from the CNS.

    Original languageEnglish (US)
    Pages (from-to)271-280
    Number of pages10
    JournalJournal of Neuroscience Research
    Volume5
    Issue number4
    DOIs
    StatePublished - 1980

    Keywords

    • enzyme regulation
    • glycine
    • methionine
    • one‐carbon metabolism
    • serine
    • serine hydroxymethyltransferase

    ASJC Scopus subject areas

    • Cellular and Molecular Neuroscience

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