5‐Methyldeoxycytidine monophosphate deaminase and 5‐methylcytidyl‐DNA deaminase activities are present in human mature sperm cells

FEBS Letters

Siegmann, Michel¹  Thiry, Stéphane¹  Jost, Jean-Pierre¹ 

[1] Friedrich Miescher Institute, Maulbeerstrasse 66, CH-4058 Basel, Switzerland

关键词: Paternal genome;    Mutations;    DNA degradation;    DNA deamination;    DNA demethylation;   

DOI  :  10.1016/S0014-5793(02)02737-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Human mature sperm cells have a high nuclease and 5-methyldeoxycytidine monophosphate (5-mdCMP) deaminase activity. The deaminase converts the nuclease degradation product 5-mdCMP into dTMP which is further cleaved into thymine and the abasic sugar-phosphate. Both 5-methylcytidine 5′ and 3′ monophosphates are good substrates for the deaminase. 5-methylcytidine is not a good deaminase substrate and 5-methylcytosine (5mC) is not a substrate. A purified fraction of the deaminase free of nucleases deaminates 5mC present in intact methylated double-stranded DNA. 5-mdCMP deaminase co-purifies on SDS–PAGE with dCMP deaminase and has an apparent molecular weight of 25 kDa. The enzyme requires no divalent cations and has a K _m of 1.4×10⁻⁷ M for 5-mdCMP and a V _max of 7×10⁻¹¹ mol/h/μg protein. The possible biological implications of the deaminase's activities in the present system are discussed.

【 授权许可】

Unknown