Racemization of Amino Acids in Marine Sediments
Racemization of Amino Acids in Marine Sediments
复制标题
海洋沉积物中氨基酸的外消旋作用
DOI：
10.1126/science.173.4000.907
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发表时间：
1971
期刊：
影响因子：
56.9
通讯作者：
P. E. Hare
中科院分区：
文献类型：
--
作者：
J. Wehmiller;P. E. Hare
异亮氨酸是从一套年代久远的深海岩心中分离出来的几种氨基酸之一，随着沉积物年龄的增长，异亮氨酸的外消旋化程度逐渐增加。在相同的pH值和温度下，沉积物中氨基酸的初始外消旋速率几乎比游离氨基酸的速率快一个数量级。观察到的动力学取决于各种成岩过程，但对于年龄小于40万年的样品，异异亮氨酸与异亮氨酸的比值似乎是一个可靠的年龄指标；对于较老的样本，结果更加模糊。在年龄大于15 × 106年的样品中，异亮氨酸是外消旋的。
Isoleucine, one of several amino acids isolated from a suite of welldated deep-sea cores, shows a progressive increase in the degree of racemization with the age of the sediment. Amino acids in sediments show an initial rate of racemization almost an order of magnitude faster than the rate observed for free amino acids at a comparable pH and temperature. The observed kinetics depend on a variety of diagenetic processes, but it appears that the ratio of alloisoleucine to isoleucine is a reliable indicator of age for samples less than 400,000 years old; for older samples the results are more ambiguous. Isoleucine is racemic in samples older than about 15 x 106 years.