Pizzarello Sandra
Arizona State University, Tempe, AZ 85287, USA.
Orig Life Evol Biosph. 2004 Feb;34(1-2):25-34. doi: 10.1023/b:orig.0000009826.76353.de.
Carbonaceous chondrites are a primitive group of meteorites, which contain abundant organic material and provide a unique natural record of prebiotic chemical evolution. This material comprises a varied suite of soluble organic compounds that are similar, sometimes identical, to those found in the biosphere, such as amino acids, carboxylic acids, and sugar derivatives. Some amino acids of this suite also show L-enantiomeric excesses, and suggest the possibility they may have contributed to terrestrial homochirality by direct input of meteoritic material to the early Earth. This optical activity appears to be limited to the subgroup of alpha-methyl amino acids which, although not common in the extant biosphere, would have been well suited to provide the early earth with both enantiomeric excesses and means for their amplification by subsequent chemical evolution. We can also envision this exogenous delivery of carbonaceous material by meteorites and comets as having coincided with the endogenous formation of prebiotic precursors and influenced their evolution by complementary reactions or catalysis.
碳质球粒陨石是一类原始陨石，含有丰富的有机物质，为生命起源前的化学演化提供了独特的自然记录。这种物质包含一系列多样的可溶性有机化合物，它们与生物圈中发现的化合物相似，有时甚至相同，如氨基酸、羧酸和糖衍生物。这一系列中的一些氨基酸也表现出L-对映体过量，这表明它们有可能通过向早期地球直接输入陨石物质而对地球的同手性产生了贡献。这种光学活性似乎仅限于α-甲基氨基酸亚组，尽管在现存的生物圈中并不常见，但它非常适合为早期地球提供对映体过量以及通过后续化学演化进行放大的方式。我们还可以设想，陨石和彗星对碳质物质的这种外源输送与生命起源前前体的内源性形成同时发生，并通过互补反应或催化作用影响了它们的演化。
