Approaches to isozyme-specific inhibitors. 16. A novel methyl-C5' covalent adduct of L-ethionine and beta,gamma-imido-ATP as a potent multisubstrate inhibitor of rat methionine adenosyltransferases.
Approaches to isozyme-specific inhibitors. 16. A novel methyl-C5' covalent adduct of L-ethionine and beta,gamma-imido-ATP as a potent multisubstrate inhibitor of rat methionine adenosyltransferases.
复制标题
同工酶特异性抑制剂的方法。
DOI：
10.1021/jm00124a026
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发表时间：
1989
影响因子：
7.3
通讯作者：
Hampton,A
中科院分区：
文献类型：
--
作者：
Vrudhula,VM;Kappler,F;Afshar,C;Ginell,SL;Lessinger,L;Hampton,A
通过一锅法S ′-O-三甲基甲硅烷基化、N6-苯甲酰化和脱甲硅烷基化容易地合成的N ′ 6-二苯甲酰基-2 ′，3 ′-O-异亚丙基腺苷被转化成相应的S ′-醛。将其用CH 2 = CHMgBr处理，脱苯甲酰化后，分别得到S ′-C-乙烯基-2 ′，3 ′-Q-异亚丙基腺苷的5 ′ S和5 ′ R差向异构体的1 ∶ 3混合物。通过5 'R差向异构体的单晶X-射线衍射分析确定构型。混合差向异构体S ′-C-乙烯基核苷的S ′-O-四氢吡喃衍生物的硼氢化反应很容易得到5 ′（S，N）-C-（2-羟乙基）-2 ′，3 ′-O-异亚丙基腺苷。用L-高半胱氨酸二钠处理其5 ′（S，f1）-C-（2-O-甲苯磺酰基）衍生物，可以容易地引入L-乙醇胺体系。采用合成甲硫氨酸-ATP加合物的方法，将α-氨基酸基团保护，在05 '端引入α-3，7-亚氨基三磷酰基，除去封闭基团，得到两种5'差向异构体的2：3混合物。它对M-2型（正常组织）和MT型（肝癌组织）的抑制作用分别为KM（ATP）/K = 520和340，并与两种底物L-蛋氨酸和Mg ATP表现出明显的竞争动力学。它对M-2和MT的抑制作用略低于硫和C5'之间少一个CH 2的同系物，并提供了形成L-甲硫氨酸-酶-加合物和MgATP-酶-加合物复合物的趋势增加的动力学证据，证据表明，MT变体甲硫氨酸腺苷转移酶（主要在大鼠腹水肝癌细胞中）是抗癌药物设计中感兴趣的哺乳动物模型靶点。2，3该酶催化L-甲硫氨酸（Met）中的硫进攻ATP的C5'端，同时排出无机三聚磷酸盐。在大多数非肝大鼠正常组织中占优势的同工酶是第二种变体，M-2。在本系列研究的过程中，可能有用的方法来设计的isozymespecific抑制剂，我们发现，抑制剂，既有效的和显着的同工酶选择性可以得到系统和相对容易地通过连接一个短的取代基的多底物加合物，这本身是一个有效的，但不是一个同工酶选择性抑制剂的适当原子。为了帮助确定这种方法的范围和局限性，我们合成了五种类型的共价键。
JV6 7^ V6-Dibenzoyl-2', 3'-0-isopropylideneadenosine, which is readily synthesized by one-pot S'-O-trimethylsilylation, N6-benzoylation, and desilylation, was converted to the corresponding S'-aldehyde. This was treated with CH2= CHMgBr to afford, after debenzoylation, a 1: 3 mixture of the5'S and 5'R epimers, respectively, of S'-C-vinyl-2', 3'-Q-isopropylideneadenosine. The configurations were established by single-crystal X-ray diffraction analysis of the 5'R epimer. Hydroboration of the S'-O-tetrahydropyranyl derivative of the mixed epimeric S'-C-vinyl nucleosides readily furnished 5'(S, ñ)-C-(2-hydroxyethyl)-2', 3'-Q-isopropylideneadenosine. Treatment of the 5'(S, fl)-C-(2-0-tosyl) derivative of this with disodium L-homocysteinate permitted facile introduction of the L-ethionine system. By means of methods developed earlier in thesynthesis of homologous methionine-ATP adducts, the-amino acid group was protected, a/3, 7-imidotriphosphoryl group was introduced at 05', and blocking groups were removed to give the title adduct as a 2: 3 mixture of itstwo 5'epimers. It was a powerful inhibitor [KM (ATP)/K¡= 520 and 340] of the M-2 (normal tissue) and MT (hepatoma tissue) forms, respectively, of the title enzyme and displayedpredominantly competitive kinetics with thetwo substrates L-methionine and Mg ATP. It inhibited M-2 and MT slightly less effectively than its homologuepossessing one less CH2 between sulfur and C5'and gave kinetic evidence of an increased tendency to form L-methionine-enzyme-adduct and MgATP-enzyme-adduct complexes.Evidence indicates that the MT variant of methionine adenosyltransferase (predominant in rat ascitic hepatoma cells) is of interest as a model mammalian target in an-ticancer drug design. 2, 3 The enzyme catalyzes attack of the sulfur of L-methionine (Met) on C5'of ATP with ex-pulsion of inorganic tripolyphosphate. The isozyme pre-dominant in most nonhepatic rat normal tissues is a second variant, M-2. In the course of the present series of studies on possibly useful approaches to the design of isozymespecific inhibitors, we found that inhibitors that are both potent and significantly isozyme-selective can be derived systematically and relatively readily by attaching a short substituent to an appropriate atom of a multisubstrate adduct which itself is a potent but not an isozyme-selective inhibitor. 4, 6 To help determine the scope and limitations of this approach we synthesized five types of covalent