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DOI	10.1016/j.epsl.2021.117071
	Oxygen isotope exchange rates between phosphate and water catalyzed by inorganic pyrophosphatase: Implications for the biogeochemical cycle of phosphorus
	Chang S.J.; Blake R.E.; Colman A.S.
发表日期	2021
ISSN	0012821X
卷号	570
英文摘要	The oxygen isotope composition of phosphate (δ18OPO4) has been widely used as (paleo)temperature and bio-signature proxies and a tracer of biogeochemical cycling of phosphorus (P). In natural aqueous systems, reactive inorganic phosphorus is dominantly present as dissolved inorganic phosphate (DIP), and reactions involving DIP are primarily carried out by microorganisms and catalyzed by enzymes. One enzyme suggested to dominate P-cycling in nature is inorganic pyrophosphatase (PPase), a ubiquitous intracellular enzyme that catalyzes oxygen (O) isotope exchange between DIP and water. Herein, we determined PPase-catalyzed O-isotope exchange rates between DIP and water over the range of typical Earth surface temperatures (3 - 37 °C) using isotope ratio mass spectrometry (IRMS). Exchange rates determined at pH 7.4 and between 3 and 37 °C, were described by first-order reaction kinetics (rate constant k = 1.51E-05 to 3.13E-04 sec−1; half-life of reaction t1/2 = 37 to 765 minutes), and strongly dependent on temperature. The temperature dependence of the exchange reaction was fitted by the Arrhenius equation, with an activation energy of 61.8 kJ/mole. The rate of PPase-catalyzed O-isotope exchange is ca. 7 - 8 orders of magnitude faster than the rate of abiotic reactions (pH 5) at 37 °C calculated by the extrapolation of high-temperature rate data. The results of this study can be used to improve the interpretation of measured δ18O values of phosphate preserved in the rock record or during biogeochemical reactions (e.g., deconvolution of simultaneous abiotic and enzymatic/microbial processes). © 2021 The Author(s)
关键词	dissolved inorganic phosphate inorganic pyrophosphatase kinetics oxygen isotope phosphorus PPase
英文关键词	Activation energy; Biogeochemistry; Catalysis; Diffusion; Dissolved oxygen; Enzyme kinetics; Finance; Kinetics; Mass spectrometry; Phosphorus; Rate constants; Biogeochemical cycle; Dissolved inorganic phosphate; Exchange rates; Inorganic phosphates; Inorganic pyrophosphatases; Isotope exchange; Oxygen isotope composition; Oxygen isotope exchange; Oxygen isotopes; Pyrophosphatases; Isotopes
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203051
作者单位	Seoul Center, Korea Basic Science Institute, Seoul, 02841, South Korea; Department of Earth and Planetary Sciences, Yale University, New Haven, CT 06511, United States; Department of Earth, Environmental and Planetary Sciences, Rice University, Houston, TX 77005, United States
推荐引用方式 GB/T 7714	Chang S.J.,Blake R.E.,Colman A.S.. Oxygen isotope exchange rates between phosphate and water catalyzed by inorganic pyrophosphatase: Implications for the biogeochemical cycle of phosphorus[J],2021,570.
APA	Chang S.J.,Blake R.E.,&Colman A.S..(2021).Oxygen isotope exchange rates between phosphate and water catalyzed by inorganic pyrophosphatase: Implications for the biogeochemical cycle of phosphorus.Earth and Planetary Science Letters,570.
MLA	Chang S.J.,et al."Oxygen isotope exchange rates between phosphate and water catalyzed by inorganic pyrophosphatase: Implications for the biogeochemical cycle of phosphorus".Earth and Planetary Science Letters 570(2021).