Kinetic studies on the glutamate:glyoxylate transaminase of Euglena gracilis
The kinetic properties of L-glutamate:glyoxylate transminase have been investigated. Glycine formation was linear with both protein concentration and incubation time. L-glutamate was the most effective amino donor. Optimal concentrations for L-glutamate and glyoxylate were 150-200 mM and 10-20 mM, r...
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| Otros Autores: | , |
| Formato: | Capítulo de libro |
| Lenguaje: | Inglés |
| Publicado: |
1996
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| Acceso en línea: | Registro en Scopus DOI Handle Registro en la Biblioteca Digital |
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| Sumario: | The kinetic properties of L-glutamate:glyoxylate transminase have been investigated. Glycine formation was linear with both protein concentration and incubation time. L-glutamate was the most effective amino donor. Optimal concentrations for L-glutamate and glyoxylate were 150-200 mM and 10-20 mM, respectively. Initial velocity studies suggested a ping-pong reaction mechanism with a K(m) value of 89.90-66.50 mM for L-glutamate and of 12.50-10.75 mM for glyoxylate. A competitive parabolic substrate inhibition by glyoxylate at concentrations greater than 20 mM was observed. A pure linear non-competitive inhibition between glyoxylate and 4,5-dioxovaleric acid (1.1-2.8 mM) was found. We show here that in vivo different enzymes exist for the transamination of glyoxylate and DOVA. |
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| Bibliografía: | Collins, N., Merrett, M.J., The localization of glycollate-pathway enzymes, Euglena (1975) Biochem. J., 148, pp. 321-328 Noguchi, T., Mori, R., Biosynthesis of porphyrin precursors in mammals. Identity of alanine: ,δ-dioxovalerate aminotransferase with alanine: Glyoxylate aminotransferase (1981) J. Biol. Chem., 256, pp. 10335-10339 Foley, T., Beale, S.I., δ-Aminolevulinic acid formation from ,δ-dioxovaleric acid in extracts of Euglena gracilis (1982) Plant Physiol., 70, pp. 1495-1502 Shioi, Y., Nagamine, M., Sasa, T., Purification and properties of L-alanine:4,5-dioxovalerate aminotransferase from Chlorella regularis (1984) Arch. Biochem. Biophys., 234, pp. 117-124 Lombardo, M.E., Araujo, L.S., Juknat, A.A., Del C. Batlle, A.M., Glutmate:4,5-dioxovaleric acid transaminase from Euglena gracilis. Kinetic studies (1989) Eur. J. Biochem., 182, pp. 657-660 Varticovski, L., Kushner, J.P., Burnham, B.F., Biosynthesis of porphyrin precursors. Purification and characterization of mammaliam L-alanine: ,δ-dioxovaleric acid aminotransferase (1980) J. Biol. Chem., 255, pp. 3742-3747 Lombardo, M.E., Araujo, L.S., Juknat, A.A., Del C. Batlle, A.M., Effect of illumination on growth, chlorophyll content and δ-aminolevulinic acid synthesis in Euglena gracilis (1988) Comp. Biochem. Physiol., 91 B, pp. 279-284 Lombardo, M.E., Araujo, L.S., Branca, A., Del C. Batlle, A.M., A method for estimating glycine in the presence of excess glutamate with o-phthaldialdehyde (1990) Z. Naturforsch., 45 C, pp. 911-914 Lowry, O.H., Rosebrough, N.J., Farr, A.L., Randall, R.J., Protein measurement with the Polin phenol reagent (1951) J. Biol. Chem., 193, pp. 265-275 Kah, A., Dörnemamm, D., Senger, H., Isolation and purification to apparent homogeneity of 4,5-dioxovalerate aminotransferase from Scenedesmus obliquus mutant C-2A′ (1988) Z. Naturforsch., 43 C, pp. 563-571 |
| ISSN: | 10111344 |
| DOI: | 10.1016/S1011-1344(96)07387-3 |