Phosphoenolpyruvate carboxylase: Difference between revisions
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== Function == | == Function == | ||
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Although all enzymes of the C4 cycle are present in C3 plants, there are important changes found in C4 isoforms, specially in PEPC enzymes, that make C4 metabolism possible. PEPC’s have several non-photosynthetic related functions in different plant tissues. In C4 plants, however, changes in the promotor and enzyme structures allow for strong and specific mesophyll expression, reduced sensitivity to negative feedback inhibitors and higher kinetic efficiency <ref name="blasing2000"/><ref>PMID: 12781769</ref><ref name="Paulus2013"/>. Without this characteristics, efficient carbon fixation in the mesophyll and subsequent carbon concentration in the BS wouldn’t be possible. Therefore, the evolution of PEPC’s C4 isoforms is one of the most important steps in the establishment of the C4 pathway <ref name="sage2004"/>. | Although all enzymes of the C4 cycle are present in C3 plants, there are important changes found in C4 isoforms, specially in PEPC enzymes, that make C4 metabolism possible. PEPC’s have several non-photosynthetic related functions in different plant tissues. In C4 plants, however, changes in the promotor and enzyme structures allow for strong and specific mesophyll expression, reduced sensitivity to negative feedback inhibitors and higher kinetic efficiency <ref name="blasing2000"/><ref>PMID: 12781769</ref><ref name="Paulus2013"/>. Without this characteristics, efficient carbon fixation in the mesophyll and subsequent carbon concentration in the BS wouldn’t be possible. Therefore, the evolution of PEPC’s C4 isoforms is one of the most important steps in the establishment of the C4 pathway <ref name="sage2004"/>. | ||
<StructureSection load='' size='400' side='right' scene='57/573979/Tetramer/1' pspeed='8'> | |||
== PEPC enzyme structure == | == PEPC enzyme structure == | ||
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[[Image:PEPC reaction mechanism.png|center|frame|caption position=bottom|'''Figure 5''' Catalytic mechanism of PEPC based on maize C4-PEPC and ''E. coli'' PEPC crystal structures and the three-step reaction model. The hydrophobic pocket is shown as yellow circles and the residues show maize numbering. Adapted from Izui et al. 2004. <ref name="Izui2004"/>]] | [[Image:PEPC reaction mechanism.png|center|frame|caption position=bottom|'''Figure 5''' Catalytic mechanism of PEPC based on maize C4-PEPC and ''E. coli'' PEPC crystal structures and the three-step reaction model. The hydrophobic pocket is shown as yellow circles and the residues show maize numbering. Adapted from Izui et al. 2004. <ref name="Izui2004"/>]] | ||
</StructureSection> | |||
== 3D structures of phosphoenolpyruvate carboxylase == | == 3D structures of phosphoenolpyruvate carboxylase == | ||