Isoleucine
- α -amino- β - methylvaleric acid
- (2S, 3S )-2 -amino-3 -methylpentan- acid
- Abbreviations: Ile ( three letter code )
- I ( single letter code )
- 73-32-5 L- isoleucine
- 319-78-8 D -isoleucine
- 443-79-8 DL -isoleucine
- 1509-34-8 L -allo- isoleucine
- 1509-35-9 D -allo- isoleucine
V06
Colorless solid with a faint odor
Fixed
Decomposition: 284 ° C (L - isoleucine)
- PKCOOH: 2.32 (25 ° C, L - isoleucine)
- PKNH2: 9.76 (25 ° C, L - isoleucine)
Soluble in water: 40 g · l-1 (20 ° C, L - isoleucine)
Template: Infobox chemical / molecular formula search available
L- isoleucine, abbreviated as Ile or I, is an essential proteinogenic α - amino acid, which belongs to the aspartate group, ie is derived from aspartic acid.
Isoleucine has two stereogenic centers, therefore there are four stereoisomers in our environment, however, only the L- isoleucine plays a role as a proteinogenic amino acid and is physiologically significant. If in this text or in the scientific literature " isoleucine " without further suffix (prefix ) is mentioned, L- isoleucine is meant.
Isoleucine belongs together with its constitutional isomers leucine, norleucine and tert -leucine to the group of leucine.
History
L- isoleucine was first isolated in 1904 by Felix Ehrlich from entzuckerter molasses.
Occurrence
Isoleucine - peptidic bound - part animal and vegetable protein. The following examples relate in each case to 100 g of the food, in addition, the percentage of isoleucine is indicated at the total protein.
All of these foods contain almost exclusively chemically bound L- isoleucine as a protein component, but no free L- isoleucine.
Properties
Isoleucine is the isoelectric point ( a certain pH value) as the zwitterion ( inner salt ) before, that is, the proton of the carboxyl group (-COOH) is dissociated and the protonated amino group (-NH2).
- Side chain: lipophilic
- Isoelectric point: 5.94
- Van der Waals volume: 124
- Lipid solubility: Log P = 4.5
Stereochemistry
Isoleucine has two stereocenters, there are thus four stereoisomers, physiologically significant, however, is only the L- isoleucine as a proteinogenic amino acid. The enantiomer of the natural L -isoleucine is the D- isoleucine. L -allo- isoleucine and its enantiomer D -allo- isoleucine are diastereomers of L-isoleucine.
- (2S, 3S )-2- amino-3- methylpentanoic acid
- (S)- isoleucine
- (2R, 3R )-2- amino-3- methylpentanoic acid
- (2R, 3R )-2- amino-3- methylvaleric acid
- (R) -isoleucine
- (2S, 3R )-2- amino-3- methylpentanoic acid
- (2R, 3S )-2- amino-3- methylpentanoic acid
Biochemical importance
On one hand, isoleucine is required as a building block for protein construction. On the other hand, it can also be used for energy production in muscle cells. The plays in protein- rich diet or a role but with longer efforts and in periods of starvation when the body draws on its own reserves. The reduction of isoleucine provides acetyl CoA and propionyl - CoA.
The estimates of the daily requirement for healthy adults range, depending on the method used, 7.5 to 28 mg of isoleucine per kilogram of body weight. In the human organism isoleucine occurs almost only in the bound state. The concentration of free isoleucine in the blood is about 7 mg / l, 10 to 15 mg in the urine excreted per day.
Extraction
L-isoleucine is mainly produced by fermentation of glucose solutions containing L-threonine. By hydrolysis of protein and subsequent release operations, a mixture of natural amino acids L- leucine and L- isoleucine. These structural isomers can be separated, for example by an enzymatic process.
Use
As a component of amino acid infusion solutions [ Aminoplasmal ® ( D), Aminosteril ®-N - Hepa (D), Primene ® ( A)] for parenteral nutrition is L- isoleucine, among other amino acids, widely used in human medicine. For patients with impaired digestive an orally applicable was developed " chemically defined diet", which contains L- isoleucine. In this diet, the amino acids are the nitrogen source; all essential nutrients are chemically well- defined shape.