Abstract

The enzymatic interconversion of serine to glycine and N5, N10-methylene tetrahydrofolate to N5 -methyl tetrahydrofolate have been studied in a cell-free system derived from bovine brain. A partial purification of serine transhydroxymethylase and N5, N10 -methylene tetrahydrofolate reductase has been achieved by ammonium sulfate fractionation, protamine sulfate fraction, and by various column chromatography procedures. The two enzymes studied catalyze sequentially the reductive transfer of the hydroxymethyl group of serine to the N5 position of tetrahydrofolate forming N5 -methyl tetrahydrofolate. The products of these reactions were assayed by the incorporation of C14 from a one-carbon precursor i.e., L-beta-(C14)-serine, or N5 -methyl (C14) tetrahydrofolate. The partial purified serine transhydroxymethylase exhibited an absorption peak at 415 mμ due to the bound pyridoxal-5-phosphate and had a maximum pH optimum at 7.6. N5, N10 -methylene tetrahydrofolate reductase is a flavoprotein with a maximum pH optimum at 6.5 and an absorption peak at 405 mμ.

Degree

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

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