ABSTRACT
Lysine has long been recognized as an essential amino acid for humans and the lack or low supply of this compound in the diet may lead to mental and physical handicaps. Since lysine is severely restricted in cereals, the most important staple food in the world, the understanding of its biological roles must be a major concern. Here we show that lysine is an important precursor for de novo synthesis of glutamate, the most significant excitatory neurotransmitter in the mammalian central nervous system. We also show that the synthesis of glutamate from lysine, which is carried out by the saccharopine pathway, is likely to take place in neurons.
Subject(s)
Brain/metabolism , Glutamic Acid/metabolism , Lysine/metabolism , Neurons/metabolism , Animals , Brain/cytology , Brain/enzymology , Cerebellum/cytology , Cerebellum/enzymology , Cerebellum/metabolism , Cerebral Cortex/cytology , Cerebral Cortex/enzymology , Cerebral Cortex/metabolism , Gene Expression Profiling , In Situ Hybridization , Mice , Neurons/enzymology , RNA, Messenger/analysis , RNA, Messenger/genetics , Saccharopine Dehydrogenases/genetics , Saccharopine Dehydrogenases/metabolismABSTRACT
With all bacteria tested, addition of phenylacetaldehyde leads to light emission. The latter is markedly stronger with gram-negative bacteria, presumably because they possess a thinner wall and an extra external lipophilic membrane. Consistent with this explanation, the bactericidal effect of phenylacetaldehyde is also stronger with gram-negative bacteria. The spectrum of the emitted light shows maximal emission in the 500 nm region and is very similar to that observed when a protein (bovine serum albumin), free amino acids or isopropylamine reacts with phenylacetaldehyde.
