Tryptophan indigo

Important indole derivatives (see Scheme 2) include (i) indigo, a vat dye known and widely used since antiquity, and originally obtained from indican, a (3-glucoside of indoxyl which occurs in some plants. Indigo is now prepared synthetically. Tyrian purple, a natural dye used since classical times, is 6,6 -dibromoindigo (ii) the numerous indole alkaloids, with complex derivatives such as yohimbine and strychnine (iii) tryptophan, an essential amino acid found in most proteins. Its metabolites include skatole and tryptamine and (iv) 3-indoleacetic acid, which is important as a plant growth hormone. 

Some chemicals such as indigo, tryptophan, and phenylalanine are overproduced in bacteria by pathway engineering (36—38). In this method, the enzymes involved in the entire pathway are overproduced. In addition, the host bacterium is also altered such that the carbon flow is directed toward the engineered pathway (38). E. coli has been modified to overproduce indigo and tryptophan and phenylalanine. Corynebacterium ghitamicum has been engineered to overproduce tryptophan from 28 to 43 g/L. Similarly, attempts are underway to overproduce several vitamins by pathway engineering (34,38). 

This is an amino acid the name of which does not have the ine termination. The beta carbon group in alanine has substituted in it the complex group, (CsHeN), which Is known as the indol radical. Indol is a benzene derivative related to indigo. Tryptophane derives its name... 

Tryptophan malabsorption (blue diaper syndrome) Indigo blue and other indoles (amino acid excretion is normal) Tryptophan Hypercalcemia, retarded growth, febrile episodes, and irritability Chromatographic separation and detection of indole derivatives (H21, S36) (D16, R9, T3a)... 

Indigo, the dye used to color blue jeans, can be made enzymatically by removal of the side chain of tryptophan to give indole, which can be dihydroxylated enzymatically, then oxidized with oxygen to indigo (9.42). 

By 1909 the chemical nature of the royal purple pigment dibromoindogotin (see scheme) had been established and by 1897 synthetic indigo production had already begun. Ancient indigo dyeing utilized the precursors, sulfate esters of indoxyl or of substituted indoxyl, metabolites of tryptophan (see Fig. 

Synthesis After A. von Baeyer achieved the first synthesis of I. in 1878 and the exact structure was elucidated in 1883, further syntheses of I. were developed, the best of which was that by Heumann in 1890. Like natural 1., synthetic I. contains the isomeric indigo red, the content of the latter ranges from 2-4% in Bengal I. to 15% in Java I. The biosynthesis proceeds from indole and/or L-tryptophan and has not been completely clarified . ... 

The biosynthesis of tryptophan branches off from chorismic acid, and was already described in the section on indigo cf. section 2.1 - Indigo). 

Other well-known indoles that have various natural sources are skatole (3-methylindole) (2), serotonin (3), L-tryptophan (4), tryptamine (5), the plant growth hormones 3-indoleacetic acid (6) and 4-chloro-3-indoleacetic acid (7) [19], the mushroom hallucinogen psilocin (8), and the indole-derived ancient dyes indigo (9) [20] and Tyrian Purple (10) [19] (Scheme 1). 

Tryptophan reacts with chlorine dioxide (195) to give a mixture containing isatin, indoxyl, indigo red, and other substances (64). Histidine also reacts (195), but the products have not been characterized. 

The transfer between B. circulans and S, kanamyceticus is not yet possible, but the technique has been used to transfer the enzyme naphthalene dioxygenase from Pseudomonas putida to Escherichia colL In . coli this dioxygenase will catalyse the oxidation of indole, which is a product of the breakdown of tryptophan. The E coli cells then excrete indoxyl which is further oxidized by air to the purple dye, indigo (Figure 6.20). This is a novel secondary metabolite for E. coli to produce, and while its utility is questionable, the effect of transferring the dioxygenase into E, coli was predicted. 

Figure 6.20 The synthesis of indigo by genetically-engineered strains of E. coli. E. coli. which naturally contains tryptophanase, oxidizes tryptophan to indole, pyruvate and ammonia. When the cells are genetically engineered so that they also contain the naphthalene dioxygenase derived from Pseudomonas putida, the indole is further oxidized to indigo.

Indigo, indirubin, indoxyl and indican which have all been found in mammalian urine are probably formed from indole, itself produced by the action of intestinal bacteria on L-tryptophan. 

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