Tryptophane constitution

In all hypotheses relating to the biogenesis of the ergoline-lysergic acid moiety of ergot alkaloids, it was assumed that tryptophan constituted a main structural element. This assumption was later shown by experiment to be correct. 

Lewis acids such as zinc triflate[16] and BF3[17] have been used to effect the reaction of indole with jV-proiected aziridine-2-carboxylate esters. These alkylations by aziridines constitute a potential method for the enantioselective introduction of tryptophan side-chains in a single step. (See Chapter 13 for other methods of synthesis of tryptophans.)... 

Indole alkaloids from Tabernaemontana plants are all biogenetically derived from tryptophan (tryptamine) and secologanine, which constitute the indole and terpenic portions, respectively, and can be classified into nine main types depending on the structural characteristics of their skeleton (Fig. 1). 

The constitution of indole and skatole had been proved by synthesis, but that of the other two compounds had not been determined, and Nencki s formulae for them were accepted. Investigations by Ellinger and Gentzen in 1903, who found that in the large intestine indole was formed in large amounts from tryptophane, but skatole only in small amounts, and that skatole only gave traces of indole under the same conditions led Ellinger to doubt the accuracy of Nencki s formulae for skatoleacetic and skatolecarboxylic acids, more especially as Wislicenus and Arnold s skatolecarboxylic acid, which was synthesised from pro-pionyl formic acid phenylhydrazone had the formula... 

A. Ellinger. Ueber die Constitution der Indolgruppe im Eiweiss. III. Oxydation des Tryptophans zu fi-Indolaldehyd. Ber., 19046, 39, 2515-2522. 

Based on the properties of the side chains, the 20 amino acids can be put into six general classes. The first class contains amino acids whose side chains are aliphatic, and is usually considered to include glycine, alanine, valine, leucine, and isoleucine. The second class is composed of the amino acids with polar, nonionic side chains, and includes serine, threonine, cysteine, and methionine. The cyclic amino acid proline (actually, an imino acid) constitutes a third class by itself. The fourth class contains amino acids with aromatic side chains tyrosine, phenylalanine, and tryptophan. The fifth class has basic groups on the side chains and is made up of the three amino acids lysine, arginine, and histidine. The sixth class is composed of the acidic amino acids and their amides aspartate and asparagine, and glutamate and glutamine. 

We must be free to eat this plant, and smell that flower, as we choose to. To deny us this right, is to deny us a simple, and basic freedom that is our Constitutional identity. If I want to continue to eat bananas and drink milk, I will do so, and get off of my back. If I want to consume tryptophan because I feel it brings me closer to God and Jesus, or makes me sleep better, I will consume tryptophan. You, the empowered authority, will not tell me not to. As was so eloquently expressed in Leonard Bernstein s West Side Story, when the hero group of heroes came up against the authority group of authorities, they said, "Hey, Officer Cronsky, fuck you."... 

The Ga effector-recognition knob is formed by residues near the a3-/15 junction. In all Ga isoforms except for Gal 3 and Gal 2, a tryptophan residue (Trp 234 in Gas) constitutes the knob that fits into a complementary cavity in the effector. Mutation of the a3 tryptophan and surrounding... 

The revised structure for clavicipitic acid, suggested earlier by King etal.,44a has been confirmed, and the stereochemistry elucidated, by X-ray crystal-structure analysis.446 The major component of the naturally occurring mixture that constitutes clavicipitic acid was obtained pure by t.l.c. on silica gel, and proves to have the (55,10/ ) stereochemistry depicted in (53). The minor component of the mixture is presumably the (55,105)-diastereoisomer. It should be noted that, at present, the absolute configuration of clavicipitic acid rests only on its biogenetic derivation from L-tryptophan.446... 

The constitution of abrine was proved by methylation with methyl iodide and methanolic sodium hydroxide, which gave the same methyl ester methiodide as did similar treatment of L-tryptophan (15). Since the product was almost completely racemized (16), this did not establish the configuration of the asymmetric center. The configurational identity of abrine and L-tryptophan was proved by Cahill and Jackson (16), who obtained the same optically pure methyl betaine (II) from both abrine and L-tryptophan by methylation with methyl iodide and methanolic sodium hydroxide. Under the appropriate conditions, the racemic methyl ester methiodide crystallized out, and was removed the methyl bfetaine (II) which remained unesterified also escaped racemization, and was recovered from the mother liquors. 

In P. semperviva it has been demonstrated that tryptophan is a precursor of psilocybin (93a). It was simultaneously suggested that a similar oxidation of tryptophan or a tryptophan metabolite at the 4-position constitutes an important intermediate stage in the biosynthesis of the ergot alkaloids from tryptophan. 

Free amino acids in musts are of paramount importance, since they constitute a source of nitrogen for yeasts in alcoholic fermentation, for lactic acid bacteria in malolactic fermentation and can also be a source of aromatic compounds. In certain cases, some amino acids can produce undesirable compounds in wines, such as ethyl carbamate, biogenic amines, ochratoxin A (from 2-phenylalanine) and 3-carbolines (from tryptophane) (Herraiz and Ough 1993 Herraiz et al. 1993). 

The observation of a chronic urticaria in two sisters who excreted abnormal amounts of xanthurenic acid after a 10-g DL-tryptophan load indicated to Knapp et al. (K6) that constitutional genetic factors may be involved in vitamin Bg-deficiency symptoms. This was borne out by a very high xanthurenic acid level during a similar test on another family. 

Figure 6. Representation of the spectral overlap relationships between the enzyme tryptophan and substrate dansyl groups, which constitute the energy donor-acceptor pair critical to observation of the ES complex (57)...

Histidine is susceptible to oxidation in the presence of metals, primarily by reaction with singlet oxygen, and this constitutes a major cause of enzyme degradation. Both histidine and tryptophan are highly susceptible to photooxidation. 

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