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Thesis (M.S.)--Michigan State University. Dept. of Plant Biology Ecology, Evolutionary Biology, and Behavior, 2008. / The direct goal of this thesis is determine the effect of expermental soil climate manipulatoins on carbon fluxes in an Alaskan rich fen and to assess the indirect influence of substrate quality on carbon mineralizaton rates in peat--From abstract. Title from PDF t.p. (viewed on July 29, 2009) Includes bibliographical references. Also issued in print.

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The United Kingdom Government has mandated ambitious carbon objectives, requiring an 80% reduction in emissions by 2050, and a 20% interim reduction by 2020. Their achievement will require government and large companies to work together, and for each to be assured of the other’s strategic intent. An emergent carbon accounting can provide reassurance if it produces credible information that supports the claims made by each party. This thesis investigates the extent to which carbon reduction narratives are supported or contradicted by actual carbon emissions disclosed in corporate accounting reports. It also investigates whether large corporations have delivered absolute carbon reductions in support of the government’s legally binding objectives. As a result of these and other investigations, the thesis contributes to the carbon accounting literature by critiquing the method of framing emissions employed by the Greenhouse Gas Protocol, the extent to which carbon reduction is supported by meaningful managerial incentives and the means by which analysts might rebalance financial return with carbon risk in portfolio construction. Following a middle ground approach, the research employs a numbers and narratives analysis in which critical alternative narratives are created at national, sectoral and firm levels. The analysis disaggregates macro carbon emissions data, and considers carbon emissions at a corporate meso and micro level. Narratives constituted out of these numbers, together with counter-narratives generated from corporate disclosures, are then evaluated to assess their credibility. The thesis adopts a practical approach, utilising multiple framing devices. In addition to reporting scopes 1, 2 and 3 carbon emissions, it describes a business model framework in which firms are expected to disclose their carbon-material stakeholder relations. Further recommendations are aimed at aligning the interests of corporate managers, investors and financial analysts with government carbon policy in order to modify behaviour and reduce emissions trajectories towards a lower carbon future.

The Morita-Baylis-Hillman (MBH) reaction is a carbon-carbon (C-C) bond forming reaction between an activated alkene and an aldehyde. It is a synthetically useful reaction due to the high atom economy and retention of multiple functional groups. Unfortunately, harsh reaction conditions are required during the MBH reaction and unpredictable product stereospecificity have hampered the widespread application of this reaction. Catalysis of the MBH reaction by enzymes has the potential to allow the reaction to occur at ambient conditions, while offering scope for improving the stereospecificity. This thesis focussed on the enzyme design of a MBH enzyme using thermostable fructose-1,6- bisphosphate (FBP) aldolases as scaffolds. These enzymes were chosen because there are common features between the aldol and MBH reactions, both making use of an enol intermediate to attack the aldehyde. In addition, aldolases typically accept a wide variety of substrates. Thermostable aldolases were selected for increased temperature tolerance creating a more desirable catalyst for industrial purposes. Thermoproteus tenax FBP aldolase (TtFBPA; WT and W144L, W144Y, K177A variants) and Staphylococcus carnosus FBP aldolase (ScFruA) were expressed and purified from E. coli. While the retro-aldol reaction catalysed by these enzymes could be easily monitored, the reverse reaction (aldol synthesis) is more difficult to quantify. Multiple methodologies for high throughput spectrophotometric detection of aldol activity were developed as a method of monitoring constructs made during directed evolution of the FBP aldolases. However, none of these proved successful in robustly determining aldol activity. The dihydroxyacetone phosphate (DHAP) mimic 1-hydroxy-3-buten-2-one phosphate (HBOP) was used to assay for MBH catalysis. While crystallographic studies with TtFBPA suggest that HBOP is bound to W144L TtFBPA in a manner compatible with the MBH reaction. NMR studies could not detect any corresponding activity. This suggests further protein engineering will be required to evolve this FBP aldolase to an MBH catalyst. In addition, our crystallographic and NMR studies with TtFBPA reveals this enzyme is capable of catalysing the formation of both FBP and tagatose-1,6-bisphosphate (TBP).Additionally, we determined the first structure of ScFruA. Interestingly, NMR experiments suggested ScFruA lacks significant control of the stereospecificity of the aldol condensation reaction and appears to catalyse the formation of FBP, TBP, xyluose-1,6- bisphosphate and psicose-1,6-bisphosphate. We conclude that while FPB aldolases could indeed provide useful scaffolds for the development of an MBH catalyst, the enzymes lack any inherent activity, necessitating the need for future creation of variants. The success of this approach will depend on the ability to screen mutant libraries for MBH product formation.

Metal-catalyzed, hydrogenative methods for carbon-carbon bond formation are attractive alternatives to traditional carbonyl addition reactions. Through in situ generation of aldehyde and organometallic species, these redox-triggered reactions circumvent the need for preactivation of reactive partners, thereby providing a more atom economic, efficient approach to carbonyl addition products. Efforts have been focused on the development of ruthenium-catalyzed coupling reactions of primary and secondary alcohols to basic feedstock chemicals and easily accessible and stable unsaturated compounds. To perform highly stereoselective reactions, investigation into the factors that control stereoselectivity in ruthenium catalyzed transfer hydrogenative couplings was undertaken. As a critical tool for the construction of organic molecules, modernizing methods for carbonyl addition can contribute to the evolution of synthetic organic methodology. / text

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