數(shù)億年前DNA和RNA分子是如何從簡單的單體聚合而成的一直是困擾生物分子起源的一個(gè)難題,。不過近日，意大利的研究人員重建了這一早期進(jìn)化過程,，僅僅在溫水存在的反應(yīng)條件下就使得簡單的核苷酸聚合成了長鏈的RNA分子,。
大多數(shù)的研究人員相信RNA分子是在DNA和蛋白質(zhì)之前出現(xiàn)的第一種生物大分子，但是很少有人成功的在生命起源以前的環(huán)境下將簡單的單體分子構(gòu)建成為RNA分子,。
Ernesto Di Mauro和他的同事發(fā)現(xiàn)在40-90°C的水中,，環(huán)核苷酸這一古老的分子能夠聚合成為長度超過100bp的分子，而這一水溫恰好與生命出現(xiàn)以前地球上水的溫度相同,。
環(huán)核苷酸與構(gòu)成DNA和RNA分子的核苷酸單體十分相似,，只是在結(jié)構(gòu)上多出了一個(gè)化學(xué)鍵而形成了環(huán)狀結(jié)構(gòu),。正是這個(gè)額外的化學(xué)鍵使得環(huán)核苷酸具有了較高的反應(yīng)活性，使得他們能夠在一定的速率下（每聚合100bp需要200小時(shí)）聚合成為長鏈核酸分子,。
由于環(huán)核苷酸可以較為容易的通過甲酰胺等簡單的化合物分子反應(yīng)而形成,，因此這使得環(huán)核苷酸在生命前期的地球環(huán)境中的大量存在成為可能。這個(gè)研究發(fā)現(xiàn)可能揭開了第一個(gè)基因組是如何產(chǎn)生的謎題,。（生物谷Bioon.com）
生物谷推薦原始出處：
JBC October 2, 2009, doi: 10.1074/jbc.M109.041905
Generation of Long RNA Chains in Water*
Giovanna Costanzo?,1, Samanta Pino§,1, Fabiana Ciciriello§ and Ernesto Di Mauro?,2
From the ?Istituto di Biologia e Patologia Molecolari, CNR,
the §Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza di Roma, and
the ?Fondazione Istituto Pasteur-Fondazione Cenci-Bolognetti, c/o Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza di Roma, P. le Aldo Moro, 5, Rome 00185, Italy
The synthesis of RNA chains from 3′,5′-cAMP and 3′,5′-cGMP was observed. The RNA chains formed in water, at moderate temperatures (40–90 °C), in the absence of enzymes or inorganic catalysts. As determined by RNase analyses, the bonds formed were canonical 3′,5′-phosphodiester bonds. The polymerizations are based on two reactions not previously described: 1) oligomerization of 3′, 5′-cGMP to ～25-nucleotide-long RNA molecules, and of 3′,5′-cAMP to 4- to 8-nucleotide-long molecules. Oligonucleotide A molecules were further extended by reciprocal terminal ligation to yield RNA molecules up to >120 nucleotides long and 2) chain extension by terminal ligation of newly polymerized products of 3′,5′-cGMP on preformed oligonucleotides. The enzyme- and template-independent synthesis of long oligomers in water from prebiotically affordable precursors approaches the concept of spontaneous generation of (pre)genetic information.
