Magnesium Isotopic Equilibrium in Chlorophylls
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- 作者：Jay R. Black ; Qing-zhu Yin ; James R. Rustad ; William H. Casey
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：July 18, 2007
- 年：2007
- 卷：129
- 期：28
- 页码：8690 - 8691
- 全文大小：54K
- 年卷期：v.129,no.28(July 18, 2007)
- ISSN：1520-5126
文摘
Photosynthesis generates ~100 gigatons of carbon per year and drives many terrestrial geochemical cycles. Magnesium is the metal center in chlorophyll and is thus central to photosynthesis. Here we report measurements of the Mg isotopic composition of chlorophylls in English Ivy (Hedera helix L.) showing that chlorophyll-a is isotopically heavier than chlorophyll-b (
26MgChla-Chlb = 0.434 ” (±0.148) and 25MgChla-Chlb = 0.241 ” (±0.108)). The measurements are consistent with electronic structure calculations of the isotopic fractionation, implying that chlorophyll-a and -b are in isotopic equilibrium. Mg isotopic equilibrium suggests that the metal is labile in these molecules during the chlorophyll cycle after the various forms of chlorophyll are biosynthesized.
26MgChla-Chlb = 0.434 ” (±0.148) and 25MgChla-Chlb = 0.241 ” (±0.108)). The measurements are consistent with electronic structure calculations of the isotopic fractionation, implying that chlorophyll-a and -b are in isotopic equilibrium. Mg isotopic equilibrium suggests that the metal is labile in these molecules during the chlorophyll cycle after the various forms of chlorophyll are biosynthesized.