Folate activity of human lymphocytes determined by measurement of serine synthesis

Journal Article · Mon Jan 01 04:00:00 EST 1973 · Scand. J. Clin. Lab. Invest., v. 31, no. 1, pp. 9-19

DOI:https://doi.org/10.3109/00365517309082412· OSTI ID:4420995

Ellegaard, J; Esmann, V

A method was developed for measuring the folate activity in isolated human lymphocytes by quantitating the incorporation of /sup 14/C-formate into serine. Isotope experiments showed that serine was formed from glucose and mainly catabolized to CO/sub 2/, NH/sub 3/, and two one-carbon fragments. Ten percent of serine is incorporated into protein and 5% is converted to metabolic acids. Small amounts were metabolized to Krebs-cycle intermediates and other amino acids and also over ethanolamine and choline to glycine. Forcing the incorporation of/ sup 14/C-formate into serine by adding 6.7 mmol/l glucose and 20 mmol/l glycine to the incubation medium gave in 24 experiments an incorporation of 9.2 plus or minus 0.4% (S.E.M.) of added formate per 10/sup 9/ lymphocytes per 4 h. The incorporation was not influenced by added pyridoxal phosphate or tetrahydrofolic acid. The effect of added serine, homocysteine, and methionine on the formate incorporation was established in model experiments, but does not appear to be of significance for the clinical applicability of the method. In 29 experiments with lymphocytes from patients with folate deficiency, the average /sup 14/C-formate incorporation into serine was 4.4 plus or minus 0.4% with practically no overlapping in the range of normal values. The extent of /sup 14/C-formate incorporation into methionine, RNA, and protein was also determined and found decreased in folate deficiency. The incorporated /sup 14/C- formate was recovered with 63% in free serine. 5% as protein-bound serine, 14% in methionine, and 18% in RNA. The same relative distribution of /sup 14/C- formate incorporation into the various products was found in folate deficiency states. (auth)

• Research Organization: Marselisborg Hospital, Aarhus, Denmark
• NSA Number: NSA-29-000896
• OSTI ID: 4420995
• Journal Information: Scand. J. Clin. Lab. Invest., v. 31, no. 1, pp. 9-19, Journal Name: Scand. J. Clin. Lab. Invest., v. 31, no. 1, pp. 9-19; ISSN SJCLA
• Country of Publication: Norway
• Language: English

Related Subjects

BIOSYNTHESIS-- CARBON 14 COMPOUNDS-- FORMIC ACID-- SERINE
FOLIC ACID-- LYMPHOCYTES-- MAN-- MEASURING METHODS-- METABOLISM-- TRACER TECHNIQUES
N48830* --Life Sciences--New Tracer Techniques--Other