D-tryptophan (Full name D (+)-Tryptophan) is a white to pale yellow or white crystalline powder at room temperature, odorless or slight odor, slightly sweet taste. Solubility in water is 1.14 g (25 ℃), soluble in dilute acid and alkali, stable in alkali, decomposed in strong acid, slightly soluble in ethanol, not soluble in chloroform, ethyl ether. It plays an important role for human and animal growth and development, metabolism, known as the second essential amino acids. They are almost identical with L-type and physical and chemical properties, and only the optical activity is opposite. But their distribution, function and coenzyme have diversity. Its melting point is very high, generally above 200 degrees. It can dissolve in water, and in the near UV region it has the ability to absorb light.
Tryptophan is one of the 20 standard amino acids, as well as an essential amino acid in the human diet. It is encoded in the standard genetic code as the codon UGG. the D-stereoisomer is occasionally found in naturally produced peptides (for example, the marine venom peptide contryphan). The distinguishing structural characteristic of tryptophan is that it contains an indole functional group. It is an essential amino acid as defined by its growth effects on rats.
