Rathnam, C K M and Edwards, G E (1975) Intracellular Localization of Certain Photosynthetic Enzymes in Bundle Sheath Cells of Plants Possessing the C4 Pathway of Photosynthesis. Archives of Biochemistry and Biophysics, 171 (1). pp. 214-225.
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Abstract
Bundle sheath cells were enzymatically isolated from representatives of three groups of C4 plants: Zea mays (NADP malic enzyme type), Panicum miliaceum (NAD malic enzyme type), and Panicum maximum (phosphoenolpyruvate (PEP) carboxykinase type). Cellular organelles from bundle sheath homogenates were partially resolved by differential centrifugation and on isopycnic sucrose density gradients in order to study compartmentation of photosynthetic enzymes. A 48-h-dark pretreatment of the leaves allowed the isolation of relatively intact chloroplasts. Enzymes that decarboxylate C4 acids and furnish CO2 to the Calvin cycle are localized as follows: NADP malic enzyme, chloroplastic in Z. mays; NAD malic enzyme, mitochondrial in all three species; PEP carboxykinase, chloroplastic in P. maximum. The activity of NAD malic enzyme in the three species was in the order of P. miliaceum > P. maximum > Z. mays. There were high levels of aspartate and alanine aminotransferases in bundle sheath extracts of P. miliaceum and P. maximum and substantial activity in Z. mays. In all three species, aspartate aminotransferase was mitochondrial whereas alanine aminotransferase was cytoplasmic. Based on the activity and localization of certain enzymes, the concept for aspartate and malate as transport metabolites from mesophyll to bundle sheath cells in C4 species of the three C4 groups is discussed.
| Item Type: | Article |
|---|---|
| Author Affiliation: | University of Wisconsin, Madison, Wisconsin 53706 USA |
| Subjects: | Plant Production Soil Science and Microbiology > Microbiology Plant Physiology and Biochemistry > Biochemistry |
| Divisions: | UNSPECIFIED |
| Depositing User: | Library ICRISAT-InfoSAT |
| Date Deposited: | 23 Feb 2012 14:12 |
| Last Modified: | 23 Feb 2012 14:12 |
| Official URL: | http://dx.doi.org/10.1016/0003-9861(75)90026-0 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/3169 |
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