Glutamine
- 2-amino -4- carbamoylbutansäure
- 2-amino -4- carbamoylbuttersäure
- Glutamic acid -5 -amide
- Abbreviations: Gln ( Three letter code)
- Q ( single letter code )
- 56-85-9 (L- enantiomer)
- 5959-95-5 (D - enantiomer)
- 585-21-7 (DL- glutamine)
Colorless and odorless solid
Fixed
185-186 ° C
- PKCOOH: 2.18 (25 ° C)
- PKNH2: 9.00 (25 ° C)
- Solubility in water: 26 g · l -1 ( 18 ° C)
- Insoluble in methanol, benzene and chloroform
7500 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
L-glutamine, abbreviated Gln or Q is a proteinogenic not essential for the human α -amino acid and γ is the mono - amide of L-glutamic acid dar. In the three-letter code and it is designated as Gln in single letter code as Q. In the metabolism of L-glutamine is an amino universal donor. In plasma glutamine comes with a content of 20% as a main component of the pool of free amino acids before. In hypercatabolic and hypermetabolic disease states, such as after surgery, severe injury, burns and infections pronounced Glutaminverarmung is always observed.
If it is mentioned in this text or in the scientific literature " glutamine " without further suffix (prefix ), L- glutamine is meant.
Stereoisomerism
In the proteins, is in addition to other amino acids, only L-glutamine [ Synonym: (S)- glutamine ] peptidically bound before. To enantiomer is the mirror image D -glutamine [ Synonym: (R) -glutamine ], which does not occur in proteins. Racemic DL -glutamine [ Synonyms: ( RS)- glutamine and ( ±) -glutamine ] has little significance.
Occurrence
Glutamine comes to an average of 3.9 % - bound in proteins - before; is also found in the free form amino acid common in all plants, animals, fungi and bacteria as a central metabolite in the metabolism of all living beings.
Foods high in glutamine are wheat ( 4.080 mg/100 g), spelled flour ( 5.170 mg/100 g), lentils ( 4.490 mg/100 g), mung beans ( 4.810 mg/100 g), soybean ( 6.490 mg/100 g), peanuts ( 5.630 mg/100 g), cheeses ( 3050-8100 mg/100 g), beef ( 4.130 mg/100 g), mutton ( 4.300 mg/100 g) and pork ( 3.910 mg/100 g). All of these foods contain almost exclusively chemically bound L- glutamine as a protein component, however, no free L-glutamine.
Properties
The colorless, crystalline glutamine is insoluble in alcohols, benzene and chloroform. However, it is sparingly soluble in water (100 g / l at 40 ° C).
- Van der Waals volume: 114
- Lipid solubility: Log P = -3.5
Glutamine is present predominantly as the "inner salt " or zwitterion, whose formation can be explained by the fact that the proton of the carboxyl group migrates to the free electron pair of the nitrogen atom of the amino group:
Zwitterions of L- glutamine ( left) and D- glutamine ( right)
In an electric field, the zwitterion migrates not because it is not loaded as a whole. Strictly speaking, this is at the isoelectric point ( at a certain pH value) of the case in which the zwitterion has its lowest solubility in water. Its isoelectric point is 5.65.
Production
Industrially, L -glutamine is produced by fermentation.
Biochemistry
For the biosynthesis including structural formulas, see section External links
L-glutamine is produced from L-glutamic acid by the glutamine synthetase. This adenosine triphosphate ( ATP) is consumed. In the body can be reduced to L- glutamine, succinate in three reaction steps.
Functions
With a proportion of 20 % glutamine main component of the pool of free amino acids in blood plasma ( 400-600 micromol / l). Glutamine is used in the highest concentration in the muscle cells ( 35 mmol / l) before, and this mainly synthesized. It is responsible among other things for the water storage in the cell and causes during exercise an increase in cell volume, which is to be regarded as an anabolic, proliferation supportive signal. That is, the protein and glycogen is promoted.
Hyperkatabole and hypermetabolic disease states are associated with a significant Glutaminverarmung in the blood and in the muscle without reactive glutamine synthesis is increased. Characteristic of the response to trauma and infection is the reduction of free glutamine in muscle by about 50%. This loss of intracellular glutamine was found irrespective of the diet both for selective operations, polytrauma and burns as well as infections and pancreatitis. Glutamine is not only a building block for protein synthesis, but, inter alia, also to the cells of the gastrointestinal tract ( enterocytes, colonocytes ) and liver cells is an important substrate, justifying the thesis was developed that glutamine a ' conditionally essential "amino acid is necessary especially for serious diseases. According to the hypothesis that glutamine supplementation in critically ill patients would lead to a better outcome was.
On the other hand showed an international multicenter randomized double -blind trial involving more than 1,200 critically ill mechanically ventilated intensive care patients with multiple organ failure, which both enterally and parenterally received glutamine in the active treatment group had a significantly increased mortality of 32.4 % (placebo 27.2 %) with an adjusted risk factor of 1.09 after 28 days. Even after six months, the mortality was significantly higher under Glutaminbehandlung but glutamine had no effect on the rate of infection or organ dysfunction. Thus, a glutamine substitution in the ICU appears obsolete and in a comment is even a " Glutamintoxizität " spoken. The reduced levels of glutamine in critically ill patients could thus be less a consequence of a defect rather than a positive adaptation mechanism.
Function in the nervous system
Glutamine is chemically closely related to the excitatory amino acid glutamic acid ( often is only spoken from the ionised form, glutamate ), which occurs as a neurotransmitter at glutamatergic synapses in the central nervous system. At these synapses, part of the glutamate is taken after the distribution in the synaptic cleft into adjacent glial cells. To transport the picked- glutamate back into the presynaptic neuron, it is converted into glutamine in the glial cells, since glutamine has no effect on excitatory postsynaptic membrane. In the neurons glutamine is then converted back to glutamate.
Function in the cell culture of tumor cells
For cell culture of many tumor cells, glutamine is necessary in high excess. As mentioned above, the human blood has a concentration of 500 to 900 mol / L glutamine, in cell culture, however, is mostly worked with 2000-4000 mu.mol / l. The reason is that many types of tumor cells significantly absorb more glutamine and metabolize than normal body cells. The reasons will be discussed in the scientific literature currently much. As a possible cause for the increased glutamine uptake and function of the tumors increased expression of the oncogene myc is proposed by various authors. Because of this dependence are different and glutamine as DON, azaserine or acivicin were tested for the treatment of various solid tumors.
Polyglutamine
A number of important proteins contain polyglutamine units, that is a long, repetitive glutamine -glutamine - links. Example of this is the FOXP2 protein or huntingtin Huntington's disease -causing. In a huntingtin caused by an autosomal dominant mutation extension of the polyglutamine unit causes the outbreak of the disease.