1-Formyl-tryptophan

Tryptophan and tryptophan-containing peptides and proteins specifically react in formic acid containing dry HCl to give the corresponding 1-formyl-tryptophan-derivative (186) (310). This modification can... 

The ultraviolet spectrum of 1-formyl tryptophan shows a maximum of absorption near 300 nm. The high yield of specific formylation of... 

For the synthesis of the natural blue pigment trichotomine dimethyl ester, L-Trp-OMe was used as a starting material. The first step of this synthesis was conversion into methyl l-methyl-3,4-dihydro-/8-carboline-3-carboxylate with acetyl chloride in TFA (85JOC3322). An improved method starts from the corresponding thioamides via thioiminium salts which cyclize spontaneously in refluxing solvent (82CPB4226). A-Formyl-tryptophan also cyclized readily with no side reactions (68CJC3404). 

Bei der Gewinnung von Tryptophan bzw. Phenylalanin aus 3-Formyl-indol bzw. Benzaldehyd und 2,4-Dioxo-imidazolidin bedient man sich der elektrochemischen Re-duktion des zunachst entstehenden Methylen-Derivats I2 ... 

Griffiths, H.R, Lunec, J. and Blake, D.R. (1992). Oxygen radical-induced fluorescence in proteins identification of the fluorescent tryptophan metabolite N formyl kynurenine as a biological index of radical damage. Amino Acids 3, 183-194. 

To 24 ml acetic anhydride in 80 ml formic acid add 22 g 4,5 or 6 methoxy (or analog) tryptophan and reflux V2 hour. Concentrate to thick syrup on steam bath with vacuum and add slowly with stirring 180 ml water and let stand twelve hours at 0°. Filter, wash with 2% HC1 and water to get about 18 g N-formyl-methoxy-tryptophan (I) (recrystallize-benzene-ethanol). 10 g (1), 119 g polyphosphoric acid,... 

A previous study of the reaction of ozone with lysoz3mie dissolved in anhydrous formic acid gave rise to the conclusion that the only amino acid residues affected in the early stages of the reaction were the tryptophan residues 108 and 111 ( ). Conversion of these residues to N -formyl-kynurenine did not cause loss in enzyme activity. Imoto et al. (7) have pointed out that this result is anomalous since modifications of tryptophan 108 (e.g. with iodine) normally causes inactivation. 

Condensation of formyl-pyrroles and -indoles with a wide range of other activated methylene compounds has been reported. These include, for example, hydantoin, which provides a useful synthetic route to tryptophane and j8- (pyrrolyl)alanines, thiohydantoin, rhodanine and AT-substituted barbituric acids (B-77MI30505, 79HC(25-3)357). Flash pyrolysis of the condensation product derived from 3-formyl-2,5-dimethylpyrrole with Meldrum s acid produces 6-hydroxy-2-methylindole, (440) — (441) (74AJC2605), whilst the analogous... 

Before cleavage with HF, those side-chain protective groups that will not be cleaved by HF must be removed (e.g. /V-formyl groups from tryptophan, A-dinitro-phenyl groups from histidine). The A-terminal Boc group is also usually removed before treatment with HF, to minimize the risk of alkylation of electron-rich function-... 

Figure 1.18 Comparison of the binding pockets in (a) chymotrypsin, with IV-formyl-L-tryptophan bound, and (b) elastase, with IV-formyl-L-alanine bound. The binding pocket in trypsin is very similar to that in chymotrypsin, except that residue 189 is an aspartate to bind positively charged side chains. Note the hydrogen bonds between the substrate and the backbone of the enzyme.

The (5)-tryptophan-derived oxazaborolidenes utilized in this aldol study have been previously examined by Corey as effective catalysts for enantioselective Diels-Alder cycloaddition reactions [6]. Corey has documented unique physical properties of the complex and has proposed that the electron-rich indole participates in stabilizing a donor-acceptor interaction with the metal-bound polarized aldehyde. More recently, Corey has formulated a model exemplified by 7 in which binding by the aldehyde to the metal is rigidified through the formation of a hydrogen-bond between the polarized formyl C-H and an oxyanionic ligand [7], The model illustrates the sophisticated design elements that can be incorporated into the preparation of transition-metal complexes that lead to exquisite control in aldehyde enantiofacial differentiation. 

Tryptophan 2,3-dioxygenase catalyzes the conversion of L-tryptophan to N-formyl-L-kynurenine. The product is further converted, both spontaneously and enzymatically, to L-kynurenine. This assay measures both products. 

The formyl group is routinely used for the protection of the tryptophan indole function in Boc/Bzl chemistry in solution and on solid support (see Section 2.6.3), and cleavage of the A -formyl derivative with HF/ethane-l,2-dithiob ° l or TFA/2-sulfanylethanoh ° l as well as by exposure to alkaline conditions (pH is well established. Less detailed information... 

Catabolism of tyrosine and tryptophan begins with oxygen-requiring steps. The tyrosine catabolic pathway, shown at the end of this chapter, results in the formation of fumaric acid and acetoaceticacid, Iryptophan catabolism commences with the reaction catalyzed by tryptophan-2,3-dioxygenase. This enzyme catalyzes conversion of the amino acid to N-formyl-kynurenine The enzyme requires iron and copper and thus is a metalloenzyme. The final products of the pathway are acetoacetyl-CoA, acetyl-Co A, formic add, four molecules of carbon dioxide, and two ammonium ions One of the intermediates of tryptophan catabolism, a-amino-P-carboxyrnuconic-6-semialdchydc, can be diverted from complete oxidation, and used for the synthesis of NAD (see Niacin in Chapter 9). 

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