Lysine

(S)- lysine
L-lysine
(R) -lysine
D-lysine
2,6- diaminohexanoic acid
Abbreviations: Lys ( Three letter code)
K ( one letter code )

56-87-1 (L- enantiomer)
923-27-3 (D - enantiomer)
70-54-2 (racemate )
657-27-2 ( monohydrochloride )

B05XB03
V06DE00

Colorless needles or hexagonal platelets

Fixed

224-225 ° C ( decomposition) (free base, enantiomer )
263-264 ° C ( monohydrochloride )
260-263 ° C ( DL -Lysine monohydrochloride )
193 ° C (L -lysine dihydrochloride)
187-189 ° C ( dihydrochloride DL -Lysine )

PKCOOH: 2.20
PKα -NH3 : 8.90
PKε -NH3 : 10.28

Template: Infobox chemical / molecular formula search available

Lysine, abbreviated as Lys or K is an essential proteinogenic α - amino acid in its natural L-form.

If in this text or in the scientific literature " lysine " without further suffix (prefix ) is mentioned, L- lysine is meant.

Properties

Together with L-arginine and L -histidine, L-lysine is one of the group of basic and both proteinogenic α -amino acids or hexon bases. Lysine has two basic primary amino groups in an α -position to the carboxy group and one in the ε - position of the side chain. The charge of the lysine is - as in all the amino acids - the pH -dependent. Lysine 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 ε -amino group, which is more basic than the α -amino group:

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 given pH value, here 9.82 ) of the case in which the lysine has also its lowest solubility in water.

Other physicochemical data for lysine are:

Isoelectric point: 9.74
Van der Waals volume of 135 Å3
Hydrophobicity: -3.9

Stereoisomerism

In the proteins, is in addition to other amino acids, only L-lysine [ Synonym: (S)- lysine ] peptidically bound before. To enantiomer is the mirror image D-lysine [ Synonym: (R) -lysine ], which does not occur in proteins. Racemic DL -lysine [ Synonyms: ( RS)- lysine and (±) -lysine ] is less important than L -lysine, but has commercial importance as a basic component in drug - salts, eg with acetylsalicylic acid.

Industrial production

Industrial several 100,000 tons of L -lysine per year are produced. L- lysine is now produced exclusively by fermentation method, although alternative organic chemical synthesis routes have been developed.

Occurrence

Lysine is an essential amino acid for humans and pigs and must be supplied in the diet. The following examples of the content of lysine are each based on 100 g of the food, in addition, the percentage is indicated on the total protein:

All of these foods contain almost exclusively chemically bound L-lysine as a protein component, however, no free L-lysine. Cereals usually contain less L -lysine shares among the amino acids of the protein component as it is optimal for human consumption.

The estimates of the daily requirement for healthy adults range, depending on the method used, from 8 to 45 mg of lysine per kilogram of body weight. An expert committee of the FAO / WHO / UNU went from a daily need between 30 mg and 64 mg per kilogram of body weight for infants and adults in 2002.

Discovery

L- lysine was first won by Edmund Drechsel by hydrolytic cleavage of casein.

Functions

Lysine is one of the amino acids, which are preferably post-translationally modified. It can get the cargo remain (mono- and di - methylation) or disappear ( acetylation ). In collagen, a modified lysine was found, the hydroxylysine with an OH group in the side chain, catalyzes the participation of the enzyme lysyl hydroxylase and the cofactor ascorbic acid ( vitamin C). Hydroxylysine allows the subsequent O-glycosylation of the collagen molecule in the endoplasmic reticulum and Golgi apparatus. Glycosylation will determine packing density of this important tissue protein and is also associated with the control of the collagen release from the cell ( exocytosis ).

A further modification is ubiquitination in proteins that are so marked for degradation by the proteasome.

In the degradation of lysine ( Eiweißfäule ) arises via pipecolic the corpse poison cadaverine ( pentamethylene ).

Use

The main quantities of industrially produced L- lysine are used in Futtermittelsupplementierung to significantly increase the nutritional value of natural feeds (cereals) with a low content of L- lysine. Racemic DL -lysine [ Synonyms: ( RS)- lysine and (±) -lysine ] has commercial importance as a basic component in drug - salts, eg with acetylsalicylic acid ( ASA).

L- lysine is a component of infusion solutions for parenteral nutrition and to treat hypochloraemic alkalosis.

Lysine is used for acceleration of analgesic active agents, particularly in combination with ibuprofen.

Biochemistry

For detailed structural formulas see also section External links

L-lysine can be degraded into two molecules of acetyl -CoA.