EFFECT OF METHIONINE, GLYCINE AND SERINE ON SERINE HYDROXYMETHYLTRANSFERASE ACTIVITY IN RAT GLIOMA AND HUMAN NEURO-BLASTOMA CELLS
EFFECT OF METHIONINE, GLYCINE AND SERINE ON SERINE HYDROXYMETHYLTRANSFERASE ACTIVITY IN RAT GLIOMA AND HUMAN NEURO-BLASTOMA CELLS
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DOI：
10.1002/jnr.490050403
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发表时间：
1980-01-01
影响因子：
4.2
通讯作者：
QUAY, WB
中科院分区：
文献类型：
--
作者：
KOHL, RL;PEREZPOLO, JR;QUAY, WB
Human neuroblastoma SK-N-SH-SY5Y (5Y) and rat glioma (C6) cells were cultured with supplemental methionine, glycine or serine for 3-6 days. Serine hydroxymethyltransferase (SHMT, EC 2.1.2.1) 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 nmol of HCHO formed per mg of protein per h, 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. SHMT-specific activity in C6 and 5Y cells is apparently not regulated by glycine, serine or methionine levels and high concentrations of these amino acids (> 30 mM) are not detrimental to these cells derived from the CNS.
