Purines, pyrimidines, and imidazoles. XXV. Some chemical reactions and interconversions of intermediates in the sequence of biosynthesis de novo of purine nucleotides leading to imidazole nucleotides.
Purines, pyrimidines, and imidazoles. XXV. Some chemical reactions and interconversions of intermediates in the sequence of biosynthesis de novo of purine nucleotides leading to imidazole nucleotides.
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嘌呤、嘧啶和咪唑。
DOI：
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发表时间：
1966
期刊：
影响因子：
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通讯作者：
G. J. Litchfield
中科院分区：
文献类型：
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作者：
M. Franks;C. Green;G. Shaw;G. J. Litchfield
对5-氨基-1-环己基咪唑-4-羧酸进行控制的温和酸处理，逐渐形成5-氨基-1-环己基咪唑、N′-环己基-α-甲酰基氨基乙脒、α-氨基-N ′-环己基乙脒（或在较高pH下α-N-甲酰基氨基-N′-环己基乙酰胺），并且在较高pH下也形成α-氨基-N ′-环己基乙酰胺。在每种情况下，用甲酸-乙酸酐洗脱，脱甲酰化反应都很容易逆转，α-氨基-N ′-环己基乙脒在缓冲水溶液中与盐酸甲酰亚胺乙酯一起迅速转化为5-氨基-1-环己基咪唑。所有中间体的结构都通过甘氨酸或氨基乙腈的交替合成来证实。用相应的5-氨基-1-β-D-呋喃核糖基咪唑-4-羧酸5′-磷酸盐观察到类似的反应序列，并讨论了结果在生物合成途径演变方面的可能意义。
Controlled mild acid treatment of 5-amino-1-cyclohexylimidazole-4-carboxylic acid leads progressively to the formation of 5-amino-1-cyclohexylimidazole, N′-cyclohexyl-α-formylaminoacetamidine, α-amino-N′-cyclohexylacetamidine (or at higher pH α-N-formylamino-N′-cyclohexylacetamide) and also at higher pH, α-amino-N′-cyclohexylacetamide. The deformylations were readily reversed in each case by formylation with formic acid–acetic anhydride, and α-amino-N′-cyclohexylacetamidine was rapidly reconverted into 5-amino-1-cyclohexylimidazole with ethyl formimidate hydrochloride in a buffered aqueous solution. The structures of all the intermediates were confirmed by alternative syntheses from glycine or aminoacetonitrile. A similar sequence of reactions has been observed with the corresponding 5-amino-1-β-D-ribofuranosyl imidazole-4-carboxylic acid 5′-phosphate and the possible significance of the results in terms of the evolution of the biosynthetic pathway is discussed.