Stable carbon isotope discrimination by form IC rubisCO from Rhodobacter sphaeroides

Le résumé fourni par la source

The C content of carbon is used to identify sources and sinks in the global carbon cycle. One enduring mystery is why the C content of marine organic carbon is relatively high. We tested the hypothesis that marine organic carbon C enrichment is due to reduced isotopic discrimination during carbon fixation by form ID RubisCOs (ribulose 1,5-bisphosphate carboxylase/oxygenase), found in a substantial portion of marine algae responsible for oceanic carbon fixation. Here, form ID RubisCO from coccolithophore Emiliania huxleyi discriminated substantially less against CO2 than other RubisCO enzymes (e=11.1‰). Reduced discrimination by form ID RubisCO may be a major factor dictating the high C content of marine organic carbon, necessitating re-evaluation of how biological δC values are integrated into global primary productivity models.

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