D-Alanine, also known as D-ala or (R)-alanine, belongs to the class of organic compounds known as alanine and derivatives. Alanine and derivatives are compounds containing alanine or a derivative thereof resulting from reaction of alanine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom.

Occurence

D-Alanine is a very strong basic compound (based on its pKa). D-Alanine exists in all living species, ranging from bacteria to humans.

Biological effects

D-Alanine is thus a central molecule in the peptidoglycan assembly and cross-linking. Three enzymes are involved in conversion of L-alanine to D-alanine and its incorporation into the UDP-rnuramyl pentapeptide; they constitute the D-alanine branch of peptidoglycan biosynthesis.

Uses

D-Alanine is the non-proteinogenic form of alanine which is used in bacterial cell wall biosynthesis. It is used to study the specificity and kinetics of alanine racemase(s) (alaR).It is used to measure the heat capacity of L-alanine single crystal.

Biosynthesis

Alanine can be synthesized from pyruvate and branched chain amino acids such as valine, leucine, and isoleucine.

Alanine is produced by reductive amination of pyruvate, a two-step process. In the first step, α-ketoglutarate, ammonia and NADH are converted by glutamate dehydrogenase to glutamate, NAD+ and water. In the second step, the amino group of the newly formed glutamate is transferred to pyruvate by an aminotransferase enzyme, regenerating the α-ketoglutarate, and converting the pyruvate to alanine. The net result is that pyruvate and ammonia are converted to alanine, consuming one reducing equivalent. Because transamination reactions are readily reversible and pyruvate is present in all cells, alanine can be easily formed and thus has close links to metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle.