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Title: OXYGEN-DEPENDENT H202 PRODUCTION BY RUBISCO

Author
item KIM, KANGMIN
item PORTIS JR, ARCHIE

Submitted to: Federation of European Biochemical Societies Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2004
Publication Date: 7/6/2004
Citation: Kim, K., Portis Jr, A.R. 2004. Oxygen-dependent H2O2 production by Rubisco. Federation of European Biochemical Societies Letters. 571:124-128.

Interpretive Summary: The activity of Rubisco, the enzyme that captures carbon dioxide, often limits photosynthesis, the process by which plants use light energy from the sun to make carbohydrates for growth from carbon dioxide and water. The activity of Rubisco is known to decline with time due to the formation of aberrant products by side reactions. In this study we show that Rubisco produces hydrogen peroxide in an oxygen-dependent manner by a side reaction not previously observed with the normal enzyme. The other product expected to be formed in this side reaction is a potent inhibitor of Rubisco activity. This information will benefit scientists attempting to modify the properties of Rubisco in ways beneficial for increased photosynthesis by crop plants.

Technical Abstract: Oxygen and ribulose 1,5-biphosphate dependent, H2O2 production was observed with several wild type Rubisco enzymes using a sensitive assay. H2O2 and D-glycero-2,3-pentodiulose-1,5-biphosphate, a known and potent inhibitor of Rubisco activity, are predicted products arising from elimination of H2O2 from a peroxyketone intermediate, specific to oxygenase activity. Parallel assays using varying CO2 and O2 concentrations revaled that the partitioning H2O2 during O2 consumption by spinach Rubisco was constant at 1/260 - 1/270. High temperatures (38 deg C), which reduces Rubisco specificity for CO2 versus O2, increased the rates of H2O2 production and O2 consumption, resulting in a small increase in partitioning to H2O2 (1/210). Two Rubiscos with lower specificity than spinach exhibited greater partitioning to H2O2 during catalysis: C. reinhardtii (1/200) and R. rubrum (1/150).