1. 4-N-hydroxy-L-2,4-diaminobutyric acid. A strong inhibitor of glutamine synthetase
S Fushiya, K Maeda, T Funayama, S Nozoe J Med Chem. 1988 Feb;31(2):480-3. doi: 10.1021/jm00397a037.
Analogues of glutamic acid were synthesized and evaluated for their inhibitory activity toward glutamine synthetase (EC 6.3.1.2; GS). The title compound, 4-N-hydroxy-L-2,4-diaminobutyric acid (NH-DABA), showed a potent inhibitory activity against GS from both sheep brain and soybean. The inhibition is competitive with respect to glutamic acid and the Ki values of sheep brain GS and soybean GS for NH-DABA are 0.007 mmol and 0.021 mmol, respectively. The activity of inhibition is comparable to those of L-methionine sulfoximine and 2-amino-4-(hydroxymethyl-phosphinyl)butyric acid (phosphinothricin).
2. The 'neurotoxicity' of L-2,4-diaminobutyric acid
R M O'Neal, C H Chen, C S Reynolds, S K Meghal, R E Koeppe Biochem J. 1968 Feb;106(3):699-706. doi: 10.1042/bj1060699.
The neurolathyrogen l-2,4-diaminobutyric acid is concentrated by liver, and liver damage can yield neurotoxicity; thus the neurotoxicity caused by this compound may be due to liver damage followed by secondary brain damage. 1. The intraperitoneal administration of toxic doses of l-2,4-diaminobutyric acid to rats resulted in hyperirritability, tremors and convulsions in 12-20hr. and increased the concentration of ammonia of blood and brain slightly and the concentration of glutamine of brain two- to three-fold. By contrast, toxic doses of l-homoarginine, l-lysine, l-leucine and ammonium acetate caused dyspnoea, extreme prostration, and in some cases coma in 15-30min., and increased the concentration of ammonia of blood significantly and the concentration of glutamine of brain slightly. These results indicate that l-2,4-diaminobutyric acid caused a chronic ammonia toxicity, whereas the other amino acids and ammonium acetate resulted in an acute ammonia toxicity. 2. Liver slices from l-2,4-diaminobutyric acid-treated animals and normal liver slices preincubated with l-2,4-diaminobutyric acid utilized ammonia and formed urea at a lower rate than control slices from normal rats. 3. l-2,4-Diaminobutyric acid inhibited competitively ornithine carbamoyltransferase of rat liver homogenates, thus demonstrating that this reaction is a primary site of toxicity for this neurolathyrogen. Although we were unable to show marked elevations of blood ammonia concentration after treatment with l-2,4-diaminobutyric acid, these results are interpreted to mean that ammonia utilization (urea synthesis) in liver is inhibited by l-2,4-diaminobutyric acid and that at least part of the neurotoxicity is due to a prolonged slight increase in body ammonia concentration.
