Relationship between nucleic acid adduct formation and deacylation of arylhydroxamic acids.
Relationship between nucleic acid adduct formation and deacylation of arylhydroxamic acids.
复制标题
核酸加合物形成与芳基异羟肟酸脱酰化之间的关系。
DOI：
10.1093/carcin/4.1.67
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发表时间：
1983
期刊：
影响因子：
4.7
通讯作者：
King,CM
中科院分区：
文献类型：
--
作者：
Glowinski,IB;Savage,L;Lee,MS;King,CM
在几个种属中，未观察到肝微粒体使芳基异羟肟酸脱酰化的能力与其将底物活化为核酸结合代谢物的能力之间存在直接关系。虽然豚鼠微粒体N-羟基-N-2-乙酰氨基芴（N-羟基-AAF）脱酰基酶比N-羟基-N-2-甲酰氨基芴（N-羟基-FAF）脱酰基酶高2倍，但N-羟基-FAF的代谢活化比N-羟基-AAF高约30倍。豚鼠肝微粒体经增溶和凝胶过滤后，核酸结合活性有两个峰，脱酰酶活性只有一个峰。虽然在峰I和峰II之间核酸与N-羟基-AAF结合的比率为10.1，但N-羟基-AAF脱酰基酶活性的比率为10.9。因此，大多数加合物是通过与脱酰作用不同的机制形成的。相对洗脱体积的比较显示，大鼠微粒体仅含有一种能够代谢活化乙酰基或甲酰基异羟肟酸的酶。豚鼠和大鼠肝胞质溶胶都具有一种具有相似相对洗脱体积的酶，其能够仅与N-羟基-FAF催化核酸加合物形成，以及一种较小的酶，其能够催化仅活化N-羟基-AAF的相同活性。豚鼠胞质溶胶还具有第三种较大的酶（在大鼠胞质溶胶中未见），其能够与任一底物进行脱酰化和核酸加合物形成。2-氨基芴（AF）（10− 3 M）使豚鼠微粒体催化的核酸与N-羟基-AAF形成加合物的峰I降低55%，峰n降低75%，而相同浓度的AF仅使峰I的脱酰酶活性降低19%。N-2-乙酰氨基芴也观察到类似的结果，但程度较低。当N-甲氧基-N-2-乙酰氨基联苯用作底物时，与N-羟基-N-4-乙酰氨基联苯（N-羟基-AABP）相比，与豚鼠肝酶的加合物形成抑制>99%。然而，惠普公司。研究表明，在与[3 H] N-羟基-AABP和GMP温育后，峰I和II都能够催化形成脱乙酰化的C-8芳基胺取代的鸟嘌呤衍生物。这些数据表明，负责加合物生产的两种豚鼠肝微粒体酶的激活机制似乎是N，O-酰基转移。
In several species, no direct relationship was observed between the abilities of liver microsomes to deacylate arylhydroxamic acids and their abilities to activate the substrates to nucleic acid binding metabolites. While guinea pig micro-somal N-hydroxy-N-2-acetylaminofluorene (N-hydroxy-AAF) deacylase is 2-fold greater than that for N-hydroxy-N-2-formylaminofIuorene (N-hydroxy-FAF), the metabolic activation of N-hydroxy-FAF is ˜ 30-fold higher than that of N-hydroxy-AAF. After solubilization and gel filtration of guinea pig liver microsomes, two peaks of nucleic acid binding activity and only one peak of deacylase activity were observed. While the ratio of nucleic acid binding with N-hydroxy-AAF between peaks I and II is ˜0.1, the ratio of N-hydroxy-AAF deacylase activities is ˜9. Thus, the majority of adducts were formed by mechanisms distinct from deacylation. Comparisons of relative elution volumes revealed that rat microsomes contain only one enzyme capable of metabolic activation of either the acetyl or formyl hydroxamic acid. Both guinea pig and rat liver cytosol possess one enzyme with similar relative elution volumes that is capable of catalyzing nucleic acid adduct formation with only N-hydroxy-FAF, and one smaller enzyme capable of catalyzing the same activity that activates only N-hydroxy-AAF. Guinea pig cytosol also possesses a third larger enzyme (not seen in rat cytosol) that is capable of both deacylation and nucleic acid adduct formation with either substrate. 2-Aminofluorene (AF) (10−3M) decreased guinea pig micro-some-catalyzed nucleic acid adduct formation with N-hydroxy-AAF by 55% with peak I and 75% with peak n, while the deacylase activity of peak I was decreased only 19% by the same concentration of AF. Similar results were seen with N-2-acetylaminofluorene but to a lesser degree. When N-methoxy-N-2-acetylaminobiphenyl was used as substrate, adduct formation with either guinea pig liver enzyme was inhibited >99% as compared with N-hydroxy-N-4-acetyl-aminobipbenyl (N-hydroxy-AABP). However, h.p.l.c. studies revealed that both peaks I and II were capable of catalyzing the formation of deacetylated C-8 arylamine-substituted guanine derivatives after incubation with [3H]N-hydroxy-AABP and GMP. These data suggest that the mechanism of activation responsible for adduct production by the two guinea pig liver microsomal enzymes appears to be N,O-acyltransfer.