Asparagine
- 2- amino-3- carbamoylpropansäure
- Abbreviations: Asn ( Three letter code)
- N ( one-letter code )
- 70-47-3 (L- enantiomer)
- 2058-58-4 (D - enantiomer)
- 3130-87-8 (DL- asparagine)
V06
Colorless solid
Fixed
- 234-236 ° C (L - asparagine)
- 182 ° C ( racemate)
- PKS1 2.1
- PKS1 8.84
Poorly in water ( 22 g · l-1 at 20 ° C, monohydrate)
Template: Infobox chemical / molecular formula search available
L-asparagine, abbreviated Asn or N is a proteinogenic α -amino acid. It is a derivative of the acidic amino acid is L -aspartic acid. She wears instead of the γ - carboxyl group of an amide group, is at the isoelectric point ( pH) as a zwitterion ( inner salt ) before and one of the hydrophilic amino acids. The abbreviations in the three- letter code and are Asn or N.
If in this text or in the scientific literature " asparagine " without further suffix (prefix ) is mentioned, L- asparagine is meant.
Stereoisomerism
In the proteins, is in addition to other amino acids, only L-asparagine [ Synonym: (S)- asparagine ] peptidically bound before. Enantiomer to this is the mirror image of D -asparagine [ Synonym: (R ) -asparagine ], which does not occur in proteins. Racemic DL -asparagine [ Synonym: ( RS)- asparagine ] has little significance.
Occurrence
L- asparagine [ Synonym ( S)- asparagine ] occurs in the seedlings of legumes and in asparagus (Asparagus officinalis).
The vegetable asparagus is also the namesake for asparagine.
Properties
Since the end of the 19th century is known that only one of the two stereoisomers ( D- asparagine) tastes sweet, and this was the reason for Louis Pasteur, to close at "the chemical asymmetry of the nervous substance ." L- asparagine tastes, however bitter.
Asparagine is present predominantly as the "inner salt " or zwitterion, the proton of the carboxyl group attaches to the lone pair of the nitrogen atom of the 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 (IEP ) of the case, which is asparagine, at a pH of 5.41. At this pH the asparagine has its lowest solubility in water.
Reactions
If the same asparagine and reducing sugars ( such as glucose ) are present in a food (especially in potatoes and cereals), at higher temperatures and low water content of acrylamide can occur, which is in the headlines because of its potentially carcinogenic effect.
Biochemistry
L- aspartic acid reacts using the asparagine and the addition of an ammonium ion of glutamine to L- asparagine. Adenosine triphosphate is required in this reaction as an energy supplier and reacts to adenosine monophosphate and pyrophosphate (PPi ). By hydrolysis of L- asparagine, L-aspartic acid in turn arises.
Use
Element of infusion solutions for parenteral nutrition.