(d)CMP, TMP, or (d)UMP + H2O => (deoxy)cytidine, thymidine, or (deoxy)uridine + orthophosphate (NT5C3)

Cytosolic 5'-nucleotidase 3 (NT5C3) catalyzes the hydrolysis of pyrimidine nucleoside monophosphates (d)CMP, TMP, and (d)UMP to nucleosides plus orthophosphate. While the enzyme appears to be present in many tissues, it is especially abundant in erythrocytes, where it may function to remove excess pyrimidine nucleotides generated by nucleic acid breakdown, while sparing purine nucleotides needed for red cell energy metabolism. Deficiencies in the enzyme are associated with a form of hemolytic anemia and its inactivation by heavy metals may be responsible for some hematological abnormalities associated with lead poisoning (Marinaki et al. 2001; Rees et al. 2003). The active form of the enzyme is a monomer. It has an absolute requirement for Mg++, and is inactive against purine nucleotides (Amici et al. 1997; Amici and Magni 2002).

细胞质5'-核苷酸酶3（NT5C3）催化嘧啶核苷单磷酸酯（d）CMP、TMP和（d）UMP的水解反应，生成核苷和正磷酸。尽管该酶在许多组织中均有存在，但在红细胞中的含量尤为丰富，其功能可能是移除由核酸分解产生的过量嘧啶核苷酸，同时保留用于红细胞能量代谢所需的嘌呤核苷酸。该酶的缺乏与一种溶血性贫血相关，且重金属对该酶的失活可能导致铅中毒相关的一些血液学异常（Marinaki等，2001；Rees等，2003）。酶的活性形式为单体，对Mg++有绝对的需求，并且对嘌呤核苷酸无活性（Amici等，1997；Amici和Magni，2002）。