NUCLEOSIDE MONOPHOSPHATE KINASE MAY BE THE KEY ENZYME PREVENTING SALVAGE OF DNA 5-METHYLCYTOSINE
NUCLEOSIDE MONOPHOSPHATE KINASE MAY BE THE KEY ENZYME PREVENTING SALVAGE OF DNA 5-METHYLCYTOSINE
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DOI：
10.1016/0027-5107(93)90186-j
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发表时间：
1993-04-01
期刊：
影响因子：
--
通讯作者：
VILPO, LM
中科院分区：
文献类型：
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作者：
VILPO, JA;VILPO, LM
核苷单磷酸激酶（EC 2.7.4.4）催化各种核苷单磷酸磷酸磷酸化为其相应的二磷酸。我们研究了5-甲基-2 '-脱氧胞苷5'-单磷酸（5 MedCMP）是否可以作为从牛肝中分离的酶的底物。尽管UMP、CMP和dCMP的底物活性是容易证明的，但是用5 MedCMP作为候选底物没有记录到活性。此外，5 MedCMP不影响酶的活性位点，因为在5 MedCMP存在下未记录到对UMP磷酸化的抑制。这一代谢步骤似乎是防止外源性5-甲基胞嘧啶（5 MeCyt）掺入DNA的关键阶段。因此，可以预期很少或没有DNA 5 MeCyt的挽救。
Nucleoside monophosphate kinase (EC 2.7.4.4) catalyzes the phosphorylation of various nucleoside monophosphates to their corresponding diphosphates. We investigated whether 5-methyl-2'-deoxycytidine 5'-monophosphate (5MedCMP) could serve as a substrate for the enzyme isolated from bovine liver. Although the substrate activity of UMP, CMP and dCMP was readily demonstrable, no activity was recorded with 5MedCMP as the candidate substrate. Morover, 5MedCMP did not affect the active site of the enzyme, since no inhibition in the phosphorylation of UMP was recorded in the presence of 5MedCMP. This metabolic step appears to be the key phase where the incorporation of exogenous 5-methylcytosine (5MeCyt) into DNA is prevented. Hence, very little or no salvage of DNA 5MeCyt can be expected.