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The Effect of Light and Exogenously Supplied Ammonium Ions on Glutamate Dehydrogenase Activity and Isoforms in Young Mustard ( Sinapis alba L.) Seedlings
Author(s) -
Lettgen W.,
Britsch L.,
Kasemir Helga
Publication year - 1989
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1989.tb00093.x
Subject(s) - sinapis , gene isoform , glutamate dehydrogenase , isozyme , seedling , biochemistry , lactate dehydrogenase , isoelectric focusing , enzyme , ammonium , cotyledon , western blot , phytochrome , dehydrogenase , biology , glutamate receptor , chemistry , botany , red light , brassica , receptor , organic chemistry , gene
Glutamate dehydrogenase (GDH, E.C. 1.4.1.3) of mustard cotyledons was investigated during the first 4 days of seedling development. The enzyme was found to be composed of seven catalytically active isoforms (each with a molecular mass of 270 kDa) which exhibited a charge heterogeneity when investigated by isoelectric focusing. Antibodies against the purified isoform 7, raised in rabbits, cross‐reacted with each of the isoforms in Western blotting experiments. In addition, each of the isoforms was composed of four immunopositive reacting polypeptides with 19, 21, 23 and 25 kDa. During development of the seedlings, a shift in the isoform pattern towards the more acidic forms was found which was more pronounced when the seedlings were supplied with 15 mM NH 4 Cl. The time course of changes in total GDH level can be correlated with the time course of disappearance of storage proteins. Both parameters are negatively regulated by light possibly via the photoreceptor, phytochrome. There are some indications that GDH in young mustard cotyledons mainly acts in the deaminating direction.