Tryptophan requirements

The two intermediates in the conversion of anthranilate to indole-3-glycerol phosphate, phosphoribosylan-thranilate and l -(O-carboxyphenylamino)-1 -deoxyribu-lose-5 phosphate, were originally postulated to account for the involvement of phosphoribosyl pyrophosphate in indole-3-glycerol phosphate formation. Support for the postulate was obtained when the dephosphorylated derivative of the second of these intermediates was found in the culture fluids of certain tryptophan-requiring bacterial mutants. The corresponding derivative of the first intermediate has not been found, probably because of its instability. Indeed, this compound, when formed in extracts, is rapidly broken down to anthranilate and ribose-5-phosphate. 

For several years, indole, which was accumulated by some mutants and used to satisfy the tryptophan requirement by others, was considered an intermediate in tryptophan biosynthesis. Such a role for indole would have been of interest, because it appeared to be an exception to the generalization that biosynthetic intermediates had to bear a charge. It was found that extracts of cells that utilized indole did indeed catalyze the condensation of indole with serine, and extracts of cells that accumulated indole catalyzed the... 

The important metaboUsm of the neurotransmitters norepinephrine, epinephrine, dopa, and serotonin involves pterin-dependent monooxygenases. The direct biocatalytic hydroxylation of the aromatic amino acids phenylalanine, tyrosine, and tryptophane requires tetrahydrobiopterin and Fe as the cofactors [60]. The cleavage of unsaturated glyceryl ethers by glyceryl ether monooxygenase also requires tetrahydrobioterin as the cofactor [61]. 

Niacin is not a true vitamin in the strictest definition since it can be derived from the amino acid tryptophan. However, the ability to utilize tryptophan for niacin synthesis is inefficient (60 mg of tryptophan are required to synthesize 1 mg of niacin). Also, synthesis of niacin from tryptophan requires vitamins Bi, B2 and Bg, which would be limiting in them on a marginal diet. 

Cysteine and tryptophan require special treatment for quantitative analysis [5]. Cystine/cysteine can be determined using three equally successful methods oxidation, alkylation, and disulfide exchange. Oxidation to... 

Enantiomerically pure 4-alkyl substituted derivatives of tryptophan required for the asymmetric syntheses of ergot alkaloids has been obtained [35]. The author used the method [36] to produce 4-alkyl substituted indoles and combined this organometallic reaction with an enantioselective enzymatic transformation. An efficient eight stage synthesis ofN-benzenesulphonyl-3-(3 -methoxyprop-2 -en-r-yl)-4-(r-hydroxy-2 -trimethylsilymethyl-prop-2 -en-r-yl)-indoles from 4-carbomethoxyindole has been described [37]. The use of these benzylic alcohols for intramolecular cation-olefine cycloadditions yielding either a tetracyclic or a tricyclic product was also demonstrated. 

While it is possible to detect proteins based on the native fluorescence of tryptophan, that amino acid is the least abundant in yeast, representing 1.0% of the total amino acid content of yeast. Excitation of tryptophan requires expensive and temperamental UV lasers. Instead, it is usually more convenient to label the protein with a fluorophore that is excited by inexpensive and reliable lasers that operate in the visible portion of the spectmm. 

Stadler, J. and Yanofsky, C. (1959) Studies on a series of tryptophan-independent strains derived from a tryptophan requiring mutant of Escherichia coli. Genetics, 44, 106-123. 

Early studies of the biosynthesis of L-tryptophan (3) established that both anthranilic acid and indole were able to replace L-tryptophan as a growth factor for some bacteria. The suggestion that these compounds were normal precursors of the aromatic amino acid was confirmed by Tatum, Bonner and Beadle " who showed that some L-tryptophan requiring mutants of Neurospora sp. responded to anthranilic acid or indole whilst others responded only to indole and accumulated anthranilic acid. Somewhat later other mutants were found which were blocked between indole and L-tryptophan and accumulated indole in the culture medium. 

Tryptophan requirements of growing pigs a dose response study... 

Eder, K., H. Nonn, H. Kluge, and S. Peganova, 2003. Tryptophan requirement ofgrowing pigs at various body weights. J. Anim. Phys. Anim. Nutr. 87, 336-346. 

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