Cookies on CAB eBooks

Like most websites we use cookies. This is to ensure that we give you the best experience possible.


Continuing to use  means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

CAB eBooks

Ebooks on agriculture and the applied life sciences from CAB International

CABI Book Chapter

Amino acids in higher plants.

Book cover for Amino acids in higher plants.


This book, divided into 5 parts, deals with topics on amino acids in higher plants. Part I (enzymes and metabolism) contains 16 chapters pursuing the theme of amino acid metabolism through the driving actions of the principal enzymes, emphasizing recent advances particularly with reference to localization, biophysical characterization and regulation. Part II (dynamics) includes two chapters design...


Chapter 1 (Page no: 1)

Glutamate dehydrogenase.

Glutamate dehydrogenase (GDH; EC. aminating activity unleashes a metabolic propulsion in crop plants that optimizes, maximizes and doubles the amino acid, protein, fatty acid, carbohydrate and dry matter yields per hectare. It is possible that the molecular biology of the enzyme may hold clues for increasing the yields of food crops for feeding a burgeoning world population without cultivating more land, without applying more fertilizer and without increasing man-hour input. GDH is historically known to catalyse the reversible reductive amination of α-ketoglutarate (α-KG) in the synthesis of l-glutamate in higher plants. It also catalyses the template-independent polymerization of nucleoside triphosphate(s) to RNA. The discovery of the aminating activity of the glutamine synthetase (GS; EC6.3.1.2)-glutamate synthase (GOGAT; EC. cycle in chloroplasts triggered new conversations and extensive research on the role of GDH in the synthesis of glutamate. The Km value for the NH4+ ion is much lower in GS than in GDH, which fact has increased understanding of the differential mechanisms of NH4+ ion assimilation and glutamate synthesis during deficit and surplus supplies of α-KG. It might appear from some repetitive experimentation on low-activity preparations of GDH that the deaminating direction is emerging as the consensus role of the enzyme. But many lines of new experimental evidence from systems biology illuminate the uninterruptible flow of α-KG via the citric acid cycle; and the nature of the aminating cassette of GDH isoenzymes reiterates and supports the amination role. Specifically, the kinetic property of GDH to discriminate and integrate the plant's environmental signals by synthesizing RNAs that regulate the mRNAs encoding many enzymes (phosphate translocator, granule-bound starch synthase, phosphoglucomutase, nitrate reductase, glycinamide ribonucleotide transformylase, etc.) of primary metabolism is the collateral chemical scaffolding on which the aminating natural role stands as it synchronizes carbon and nitrogen metabolic pathways, and assimilates exponential multiples of kilogram quantities of NH4+ ion as assimilated via the GS-GOGAT cycle during normal to maximum photosynthetic supplies of C3, C5, etc. compounds. GDH possibly deaminates vanishing fractions of glutamate as it synthesizes RNA that regulates the mRNAs so that glutamate biosynthesis is not shut down during low to normal flow of C3, C5, etc. compounds of photosynthesis. Ammonium ion assimilation and glutamate synthesis by GDH are regulated in higher plants by the supply of NH4+ ions, and the flow of α-KG from the citric acid cycle to GDH, not by the reverse-flow of α-KG from glutamate.

Other chapters from this book

Chapter: 2 (Page no: 30) Alanine aminotransferase: amino acid metabolism in higher plants. Author(s): Raychaudhuri, A.
Chapter: 3 (Page no: 57) Aspartate aminotransferase. Author(s): Leasure, C. D. He, Z. H.
Chapter: 4 (Page no: 68) Tyrosine aminotransferase. Author(s): Hudson, A. O.
Chapter: 5 (Page no: 82) An insight into the role and regulation of glutamine synthetase in plants. Author(s): Sengupta-Gopalan, C. Ortega, J. L.
Chapter: 6 (Page no: 100) Asparagine synthetase. Author(s): Duff, S. M. G.
Chapter: 7 (Page no: 129) Glutamate decarboxylase. Author(s): Molina-Rueda, J. J. Garrido-Aranda, A. Gallardo, F.
Chapter: 8 (Page no: 142) L-arginine-dependent nitric oxide synthase activity. Author(s): Corpas, F. J. Río, L. A. del Palma, J. M. Barroso, J. B.
Chapter: 9 (Page no: 156) Ornithine: at the crossroads of multiple paths to amino acids and polyamines. Author(s): Majumdar, R. Minocha, R. Minocha, S. C.
Chapter: 10 (Page no: 177) Polyamines in plants: biosynthesis from arginine, and metabolic, physiological and stress-response roles. Author(s): Mattoo, A. K. Fatima, T. Upadhyay, R. K. Handa, A. K.
Chapter: 11 (Page no: 195) Serine acetyltransferase. Author(s): Watanabe, M. Hubberten, H. M. Saito, K. Hoefgen, R.
Chapter: 12 (Page no: 219) Cysteine homeostasis. Author(s): García, I. Romero, L. C. Gotor, C.
Chapter: 13 (Page no: 234) Lysine metabolism. Author(s): Medici, L. O. Nazareno, A. C. Gaziola, S. A. Schmidt, D. Azevedo, R. A.
Chapter: 14 (Page no: 251) Histidine. Author(s): Ingle, R. A.
Chapter: 15 (Page no: 262) Amino acid synthesis under abiotic stress. Author(s): Planchet, E. Limami, A. M.
Chapter: 16 (Page no: 277) The central role of glutamate and aspartate in the post-translational control of respiration and nitrogen assimilation in plant cells. Author(s): O'Leary, B. Plaxton, W. C.
Chapter: 17 (Page no: 298) Amino acid export in plants. Author(s): Price, M. B. Okumoto, S.
Chapter: 18 (Page no: 315) Uptake, transport and redistribution of amino nitrogen in woody plants. Author(s): Pfautsch, S. Bell, T. L. Gessler, A.
Chapter: 19 (Page no: 340) Auxin biosynthesis. Author(s): Chandler, J. W.
Chapter: 20 (Page no: 362) Involvement of tryptophan-pathway-derived secondary metabolism in the defence responses of grasses. Author(s): Ishihara, A. Matsukawa, T. Nomura, T. Sue, M. Oikawa, A. Okazaki, Y. Tebayashi, S.
Chapter: 21 (Page no: 390) Melatonin: synthesis from tryptophan and its role in higher plant. Author(s): Arnao, M. B. Hernández-Ruiz, J.
Chapter: 22 (Page no: 436) Glucosinolate biosynthesis from amino acids. Author(s): Stotz, H. U. Brown, P. D. Tokuhisa, J.
Chapter: 23 (Page no: 448) Natural toxins that affect plant amino acid metabolism. Author(s): Duke, S. O. Dayan, F. E.
Chapter: 24 (Page no: 461) Glyphosate: the fate and toxicology of a herbicidal amino acid derivative. Author(s): Saltmiras, D. A. Farmer, D. R. Mehrsheikh, A. Bleeke, M. S.
Chapter: 25 (Page no: 481) Amino acid analysis of plant products. Author(s): Rutherfurd, S. M.
Chapter: 26 (Page no: 497) Metabolic amino acid availability in foods of plant origin: implications for human and livestock nutrition. Author(s): Levesque, C. L.
Chapter: 27 (Page no: 507) Toxicology of non-protein amino acids. Author(s): D'Mello, J. P. F.
Chapter: 28 (Page no: 538) Delivering innovative solutions and paradigms for a changing environment. Author(s): D'Mello, J. P. F.

Chapter details