Tapiero H, Mathé G, Couvreur P, Tew KD, et al.
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie. Date of publication 2002 Nov 1;volume 56(9):446-57.
1. Biomed Pharmacother. 2002 Nov;56(9):446-57.
II. Glutamine and glutamate.
Tapiero H(1), Mathé G, Couvreur P, Tew KD.
Author information:
(1)Faculté de pharmacie, Université de Paris, CNRS UMR 8612, 5, rue
Jean-Baptiste-Clément, 94200 Chatenay-Malabry, France. haimtapiero@aol.com
Glutamine and glutamate with proline, histidine, arginine and ornithine, comprise
25% of the dietary amino acid intake and constitute the "glutamate family" of
amino acids, which are disposed of through conversion to glutamate. Although
glutamine has been classified as a nonessential amino acid, in major trauma,
major surgery, sepsis, bone marrow transplantation, intense chemotherapy and
radiotherapy, when its consumption exceeds its synthesis, it becomes a
conditionally essential amino acid. In mammals the physiological levels of
glutamine is 650 micromol/l and it is one of the most important substrate for
ammoniagenesis in the gut and in the kidney due to its important role in the
regulation of acid-base homeostasis. In cells, glutamine is a key link between
carbon metabolism of carbohydrates and proteins and plays an important role in
the growth of fibroblasts, lymphocytes and enterocytes. It improves nitrogen
balance and preserves the concentration of glutamine in skeletal muscle.
Deamidation of glutamine via glutaminase produces glutamate a precursor of
gamma-amino butyric acid, a neurotransmission inhibitor. L-Glutamic acid is a
ubiquitous amino acid present in many foods either in free form or in peptides
and proteins. Animal protein may contain from 11 to 22% and plants protein as
much as 40% glutamate by weight. The sodium salt of glutamic acid is added to
several foods to enhance flavor. L-Glutamate is the most abundant free amino acid
in brain and it is the major excitatory neurotransmitter of the vertebrate
central nervous system. Most free L-glutamic acid in brain is derived from local
synthesis from L-glutamine and Kreb's cycle intermediates. It clearly plays an
important role in neuronal differentiation, migration and survival in the
developing brain via facilitated Ca++ transport. Glutamate also plays a critical
role in synaptic maintenance and plasticity. It contributes to learning and
memory through use-dependent changes in synaptic efficacy and plays a role in the
formation and function of the cytoskeleton. Glutamine via glutamate is converted
to alpha-ketoglutarate, an integral component of the citric acid cycle. It is a
component of the antioxidant glutathione and of the polyglutamated folic acid.
The cyclization of glutamate produces proline, an amino acid important for
synthesis of collagen and connective tissue. Our aim here is to review on some
amino acids with high functional priority such as glutamine and to define their
effective activity in human health and pathologies.
DOI: 10.1016/s0753-3322(02)00285-8
PMID: 12481981 [Indexed for MEDLINE]
