Alginate gel-entrapped cells of auxotrophic thymine-dependent strain of E. coli catalyze the transfer of 2-deoxy-D-ribofuranosyl moiety of 2'-deoxyuridine to purine and pyrimidine bases as well as their aza and deaza analogs. All experiments invariably gave β-anomers; in most cases, the reaction was regiospecific, affording N9-isomers in the purine and N1-isomers in the pyrimidine series. Also a 2,3-dideoxynucleoside can serve as donor of the glycosyl moiety. The acceptor activity of purine bases depends only little on substitution, the only condition being the presence of N7-nitrogen atom. On the other hand, in the pyrimidine series the activity is limited to only a narrow choice of mostly short 5-alkyl and 5-halogeno uracil derivatives. Heterocyclic bases containing amino groups are deaminated; this can be avoided by conversion of the base to the corresponding N-dimethylaminomethylene derivative which is then ammonolyzed. The method was verified by isolation of 9-(2-deoxy-β-D-ribofuranosyl) derivatives of adenine, guanine, 2-chloroadenine, 6-methylpurine, 8-azaadenine, 8-azaguanine, 1-deazaadenine, 3-deazaadenine, 1-(2-deoxy-β-D-ribofuranosyl) derivatives of 5-ethyluracil, 5-fluorouracil, and 9-(2,3-dideoxy-β-D-pentofuranosyl)hypoxanthine, 9-(2,3-dideoxy-β-D-pentofuranosyl)-6-methylpurine, and other nucleosides.
藻酸盐凝胶包埋的辅助胸腺
嘧啶依赖菌株
大肠杆菌细胞催化2'-脱氧尿
嘧啶的
2-脱氧-D-核糖呋喃基团转移到
嘌呤和
嘧啶碱基以及它们的氮杂和去氮类似物。所有实验都不可避免地产生β-异构体;在大多数情况下,反应是区域特异性的,产生
嘌呤中的
N9-异构体和
嘧啶系列中的
N1-异构体。此外,2,3-二脱氧核苷酸可以作为糖基团的供体。
嘌呤碱基的受体活性仅在取代上有少许影响,唯一的条件是存在
N7-氮原子。另一方面,在
嘧啶系列中,活性仅限于大多数短链5-烷基和5-卤代尿
嘧啶衍
生物的狭窄选择。含
氨基的杂环碱基会发生脱
氨作用;可以通过将碱基转化为相应的
N-
二甲氨基甲烯基衍
生物来避免这种情况,然后进行
氨解作用。该方法通过分离
腺嘌呤、
鸟嘌呤、2-
氯腺嘌呤、
6-甲基嘌呤、
8-氮杂腺嘌呤、8-氮杂
鸟嘌呤、1-去氮
腺嘌呤、3-去氮
腺嘌呤的9-(2-脱氧-β-
D-核糖呋喃基)衍
生物,5-乙基尿
嘧啶、5-
氟尿
嘧啶的1-(2-脱氧-β-
D-核糖呋喃基)衍
生物,以及9-(2,3-二脱氧-β-D-戊
呋喃基)缺氧
嘌呤、9-(2,3-二脱氧-β-D-戊
呋喃基)-
6-甲基嘌呤和其他核苷酸的验证。