科學(xué)家報(bào)告說(shuō)，他們發(fā)現(xiàn)了一種可能在數(shù)億年前讓地球上的生命奇妙而專一地選擇了所謂的左手氨基酸的“祖先夏娃”晶體。蛋白質(zhì)的這些基本單元分為兩種形式——左手和右手——就像互為鏡像的一雙手,。他們的這項(xiàng)研究可能有助于解決生命起源的最令人困惑的謎題之一，該研究發(fā)表在了美國(guó)化學(xué)會(huì)的《晶體生長(zhǎng)與設(shè)計(jì)》雙月刊上。
Tu Lee 和Yu Kun Lin指出，原始地球的環(huán)境具有形成同等數(shù)量的左手和右手氨基酸的同等幾率,。然而，當(dāng)最初的生命在30多億年前形成的時(shí)候,，蛋白質(zhì)的所有氨基酸都是左手構(gòu)造的,。這種模式一直持續(xù)到了現(xiàn)代動(dòng)植物。
這組科學(xué)家在實(shí)驗(yàn)室實(shí)驗(yàn)中使用左手和右手的天冬氨酸（一種氨基酸）的混合物研究了溫度和其他條件如何影響了這種物質(zhì)的晶體形成,。他們發(fā)現(xiàn)在原始地球可能存在的條件下,，左手天冬氨酸晶體可能在大尺度上很容易地形成。“天冬氨酸晶體然后確實(shí)能夠成為單一的母晶體,，也就是整個(gè)左手群體的祖先夏娃,，”這篇文章說(shuō)。(生物谷Bioon.com)
生物谷推薦原文出處：
Cryst. Growth Des. DOI: 10.1021/cg901219f
The Origin of Life and the Crystallization of Aspartic Acid in Water
Tu Lee* and Yu Kun Lin
Department of Chemical and Materials Engineering, National Central University, 300 Jhong-Da Road, Jhong-Li City 320, Taiwan, R.O.C.
The unusual molecular complexation of the enantiomers of aspartic acid in water was discovered and proven by a solubility test, solution freezing point, crystallization kinetics, and the incubation time change. The transformation of a “conglomerate solution” (CS) to a “racemic compound solution” (RCS) was dependent on both temperature and time. The CS was the solution phase which produced conglomerate crystals, and the RCS was the solution phase which gave a racemic compound. Fourier transformed infrared spectroscopy and powder X-ray diffraction were used to characterize aspartic acid solids crystallized from those complex solution phases and to distinguish conglomerate crystals from a racemic compound. We found that it took more than 36 h at 25 °C and 5 h at 45 °C just to complete the solution phase transformation of the CS of aspartic acid to the RCS of aspartic acid. However, the presence of an equimolar of succinic acid could hinder the solution phase transformation of the CS of aspartic acid to the RCS of aspartic acid for up to at least 8 h at 60 °C. This leeway of hours had provided an opportunity for the thermodynamically stable racemic aspartic acid to convert into the metastable conglomerate in water first by either a rapid acid?base reaction or the addition of an antisolvent with the temperature drop, without being concerned by its back conversion later to a racemic compound thermodynamically for quite some time. As a result, enantioseparation of aspartic acid by preferential crystallization in a large scale would have been very common and easy to occur on the primitive earth.
