Glutamate dehydrogenase of the germinating triticale seeds: gene expression,activity distribution and kinetic characteristics |
| |
Authors: | Agnieszka Grabowska Marcin Nowicki Joanna Kwinta |
| |
Institution: | (1) Department of Biochemistry, Faculty of Agriculture and Biology, Warsaw University of Life Science, 159 Nowoursynowska St, 02-776 Warsaw, Poland;(2) Department of Genetics, Breeding, and Biotechnology, Research Institute of Vegetable Crops, 1/3 Konstytucji 3 Maja St, 96-100 Skierniewice, Poland |
| |
Abstract: | On the cross-roads of main carbon and nitrogen metabolic pathways, glutamate dehydrogenase (GDH, E.C. 1.4.1.2) carries out
the reaction of reductive amination of 2-oxoglutarate to glutamate (the anabolic activity; NAD(P)H–GDH), and the reverse reaction
of oxidative deamination of glutamic acid (the catabolic activity; NAD(P)+–GDH). To date, there have been no reports on identification of GDH genes in cereals. Here, we report cloning and biochemical characterization of the GDH from germinating triticale seeds, a
common Polish cereal. A single TsGDH1 gene is 1,620 bp long, while its 1,236 bp long open reading frame encodes a protein of 411 amino acids of high homology with
the published GDH protein sequences from other plants. Phylogenetic analyses locate the TsGDH1 among other monocotyledonous
proteins and among the sequences of the β-type subunit of plant GDHs. Changes in TsGDH1 expression and the dynamics of enzyme activity in germinating seeds confirm the existence of one TsGDH isoform with varying
expression and activity patterns, depending on the tissue localization and stage of germination. The four-step purification
method (including the anionite chromatography using HPLC) resulted in a protein preparation with a high-specific activity
and purification factor of approx. 230. The purified enzyme exhibited an absolute specificity towards 2-oxoglutarate (NAD(P)H–GDH),
or towards l-glutamate in the reverse reaction (NAD(P)+–GDH), while its low K
m constants towards all substrates and co-enzymes may suggest its aminating activity during germination, or, alternatively,
its capability to adjust the direction of the catalyzed reaction according to the metabolic necessity. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|