Premium
Isotopic discrimination between 3 H and 14 C in vitro during enzymatic phosphorylation of labelled thymidine
Author(s) -
BaugnetMahieu L.,
Goutier R.,
Semal M.
Publication year - 1966
Publication title -
journal of labelled compounds
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0022-2135
DOI - 10.1002/jlcr.2590020108
Subject(s) - phosphorylation , incubation , enzyme , in vitro , substrate (aquarium) , chemistry , thymidine , biochemistry , kinase , microbiology and biotechnology , biology , ecology
We compare the phosphorylation of 6‐ 3 H‐TdR and 2‐ 14 C‐TdR to TMP, TDP and TTP by tissue extracts and to TMP by purified kinase preparations. The rate of phosphorylation of 6‐ 3 H‐TdR is only 0.6 to 0.8 that of 2‐ 14 C‐TdR. The same isotopic discrimination exists between methyl‐labelled thymidines. In mixtures of 3 H‐TdR and 14 C‐TdR incubated together with a liver extract, the isotopic ratio is lower in the products than in the substrate. Degradation products of 3 H‐TdR do not seem to interfere with enzymatic activity. This isotopic discrimination is tentatively ascribed to an isotopic effect of 3 H which is mainly detectable at the high substrate/enzyme ratios prevailing in the in vitro incubation conditions.