NUCLEOSIDE PHOSPHOTRANSFERASE ACTIVITY OF HUMAN COLON-CARCINOMA CYTOSOLIC 5'-NUCLEOTIDASE
NUCLEOSIDE PHOSPHOTRANSFERASE ACTIVITY OF HUMAN COLON-CARCINOMA CYTOSOLIC 5'-NUCLEOTIDASE
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DOI：
10.1016/0003-9861(91)90125-3
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发表时间：
1991-12-01
影响因子：
3.9
通讯作者：
IPATA, PL
中科院分区：
文献类型：
--
作者：
TOZZI, MG;CAMICI, M;IPATA, PL
从人结肠癌提取物中分离到一种5′-核苷酸酶，它优先作用于IMP和GMP。该酶活性还催化5′-核苷单磷酸（主要是5′-IMP、5′-GMP及其脱氧对应物）的磷酸基团转移至核苷（优选肌苷和脱氧肌苷，但也催化核苷类似物，如8-氮杂鸟苷和2′，3 ′-双脱氧肌苷）。有人提出，酶的作用机制包括形成磷酸化酶作为中间体，它可以将磷酸基团转移到水或核苷上。该酶被一些效应物激活，如ATP和2，3-二磷酸甘油酸。结果表明，这些活化剂的作用主要是有利于磷酸化中间体的磷酸转移到核苷（即，核苷磷酸转移酶活性）。这一发现与以前的建议一致，即胞质5′-核苷酸酶不能被认为是一种纯的分解代谢酶。
A cytosolic 5′-nucleotidase, acting preferentially on IMP and GMP, has been isolated from human colon carcinoma extracts. This enzyme activity catalyzes also the transfer of the phosphate group of 5′-nucleoside monophosphates (mainly, 5′-IMP, 5′-GMP, and their deoxycounterparts) to nucleosides (preferentially inosine and deoxyinosine, but also nucleoside analogs, such as 8-azaguanosine and 2′,3′-dideoxyinosine). It has been proposed that the enzyme mechanism involves the formation of a phosphorylated enzyme as an intermediate which can transfer the phosphate group either to water or to the nucleoside. The enzyme is activated by some effectors, such as ATP and 2,3-diphosphoglycerate. Results indicate that the effect of these activators is mainly to favor the transfer of the phosphate of the phosphorylated intermediate to the nucleoside (i.e., the nucleoside phosphotransferase activity). This finding is in accordance with previous suggestions that cytosolic 5′-nucleotidase cannot be considered a pure catabolic enzyme.