FURTHER EVIDENCE OF THE COMPLEXITY OF THE RACEMIZATION PROCESS IN FOSSIL SHELLS WITH IMPLICATIONS FOR AMINO-ACID RACEMIZATION DATING
FURTHER EVIDENCE OF THE COMPLEXITY OF THE RACEMIZATION PROCESS IN FOSSIL SHELLS WITH IMPLICATIONS FOR AMINO-ACID RACEMIZATION DATING
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DOI：
10.1016/0016-7037(87)90097-4
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发表时间：
1987-04-01
影响因子：
5
通讯作者：
GRIFFIN, CV
中科院分区：
文献类型：
--
作者：
KIMBER, RWL;GRIFFIN, CV
利用南澳南部现代、全新世和更新世海洋沉积物中的牡蛎（Ostrea）、阿纳达拉（Anadara）和Katelysia属（Katelysia spp）的贝壳进行模拟老化实验，进一步了解了利用氨基酸D/L比值进行定量年龄测定的困难。有证据表明，外消旋化的进展，监测D/L比随时间的变化，不仅是非线性的，但也可以被逆转，表现出减少所观察到的外消旋化程度。观察到的D/L比值随时间的变化根据贝壳的年龄和属以及所检测的氨基酸而不同。卡特里西亚属给出了比Ostrea或Anadara更少的可变值，并且类似地，缬氨酸外消旋化和异亮氨酸差向异构化的可变性远小于天冬氨酸外消旋化。
Simulated aging experiments with shells of Ostrea, Anadara and Katelysia spp from Modern, Holocene and Pleistocene marine sediments in southern South Australia give further insight into the difficulties in using D/L ratios of amino acids for quantitative age determinations. Evidence is given that the progress of racemization, as monitored by changes in D/L ratios with time, is not only non-linear but also may be reversed, demonstrating a decrease in the observed degree of racemization. The observed changes in D/L ratio with time differ according to the age and the genus of shell, and the amino acid examined. Katelysia spp. gives less variable values than Ostrea or Anadara and similarly valine racemization and isoleucine epimerization are far less variable than aspartic racemization.