Tryptophane biochemical structure

Gasymov, O.K., et al. 1999. Binding studies of tear lipocalin the role of the conserved tryptophan in maintaining structure, stability and ligand affinity. Biochem Biophys Acta 1433 307. 

Tryptophan synthase (EC 4.2.1.20) from bacteria is a classic multienzyme complex that channels a metabolic intermediate (for reviews and commentaries see 1-6)). Structure/ function analysis of tryptophan synthase was pioneered by genetic and biochemical investigations beginning in the mid-1940 s. This chapter emphasizes the relationship between the function of tryptophan synthase and the three-dimensional structure of the tryptophan synthase 02)82 complex from Salmonella typhimurium7,8) and focuses on studies carried out since a recent review.6 ... 

Kynurenine. a,2-Diamino 7 OXobenzenebutanoic acid 3-a nth rani] oy] alanine. CIDHl2N,0, mol wt 208.21. C 57.68%, H 5.81%, N 13.46%. O 23.05%. An amino acid produced in ihe body frnm tryptophan, lsoln from urine o[ rabbits that had been fed tryptophan Matsuoka, Yoshimat-su, Z. Physio/. Chem. 143, 206 (1925) Butenandl et ai, ibid. 279, 27 (1943) Heidelberger el al, J. Biol, Chem, 179, 143 (1949). Structure and synthesis Butenandt et at., loc. cit. Laboratory prepn hy oxidation of L-iryptophan with a Pseudomonas sp. Hayaishi, Meister, Biochem. Prepn. 3, 108... 

Biochemical applications have been made more recently O, ). Here, cyclic photochemical reactions are employed to generate nuclear spin-polarization in biological macromolecules. The information obtained is of a structural nature rather than mechanistic. In the case of proteins aromatic amino acid residues (tyrosine, histidine and tryptophan) can be polarized by reversible hydrogen atom or electron transfer reactions with a photo-excited dye. These reactions require direct contact of the dye with the amino acid side-chains so that they only occur for residues lying at the surface of the protein. 

Psychiatric disorders (in so far as they can be explained by imbalances in neurochemicals) that accompany some of the porph)oias may be caused by a build-up in levels of ALA, which bears a structural resemblance to the neurotransmitter GABA (y-aminobutyric acid), and so could act as a neurotoxin. The heme deficiency that is brought on by the porphyrias, can lead to a reduction in the activity of hepatic (liver) enzymes that require heme. For example, reduction in the level of hepatic tryptophan pyrrolase activity leads to a build-up in levels of the amino acids tryptophan and 5-hydroxy-tryptophan. Thus, a heme-deficient state in the liver could produce biochemical abnormalities capable of leading to neurological dysfunction, while heme deficiency in nerve tissue could directly alter nerve function. This has led to the treatment of severe neurological dysfunction by intravenous administration of heme compounds. 

Discussions of biochemical fluorescence h uently start with the subject of wot n fluorescence. Hiis is because, among biopolymers. wotons are unique in dis rf ing useful intrinsic fluorescMice. Lipids, membranes, and saccharides are essenrially nonfluoresc t. and the intrinsic fluorescence of DNA is too weak to be useful In proteins, the three anxnatic amino acids— dienylalanine. t osine. and try ptc han—are all fluorescent A favorable feature of protein structure is that these three amino acids are relatively rare in proteins. Tryptophan, which is the dominant intrinsic fluorophore, is generally present at about 1 mol % in proteins. A protein may possess just one or a few tryptophan residues, which facilitates interpretation of the spectral data. If all 20 amino acids were fluorescent, it is probable that arotein emission would be too complex to int ret. 

The crystal structure of tryptophan synthase was retrieved from the Brookhaven Protein data bank see Schneider TR, Gerhardt E, Lee M, Liang P-H, Anderson KS, Schlichting I (1998) Biochem 37 5394... 

A more recently established potential precursor of indoleacetic acid is the unusual compound named ascorbigen by its Czech discoverers. This substance is found in Cruciferae and releases ascorbic acid on hydrolysis. When indole compounds including indoleacetic acid were also found among the products of chemical hydrolysis, a tentative structure could be formulated (XXVII). Studies of ascorbigen and indoleacetic acid levels show certain parallelisms and radioactive tryptophan labels both compoundsIt seems certain therefore that a biochemical linkage exists, but the nature of the intermediate steps can only be hypothesized at the present time. 

Actually there are no good definitions of alkaloids (Bate-Smith and Swain, 1966) since each one is either too narrow or too broad. Even in the restricted Winterstein and Trier definition, at least five alkaloid families exist that can be derived from different amino acids consequently, there is a need to establish the proper biosynthetic pathways to permit the application of the alkaloid character to chemotaxonomy, It has been mentioned above that canadine (berberidine) may be found in plants of six partially unrelated botanical families. This fact is not surprising when considered in relation to the biochemical investigations of canadine biosynthesis. Many reactions are necessary to convert tyrosine into canadine consequently, one might even wonder why the distribution of this alkaloid is so limited. In contrast, other plants (and even some that produce canadine) can produce many alkaloids that are derived from tyrosine but have a marked difference in structure. Tyrosine serves as the key precursor of alkaloids of the isoquinoline type, but other types of alkaloids, such as colchicine and the Amaryllidaceae and the Erythrina alkaloids, may be synthesized from this amino acid. The nucleus of an alkaloid molecule can arise from different precursors thus the indole nucleus in Erythrina alkaloids arises from tyrosine, while in brucine it comes from tryptophan (Figure 1.5). The alkaloids cinchonamine and cinchonine differ in that cinchonamine has an indole nucleus, while cinchonine (like quinine) has a quinoline nucleus however, they exist in a precursor-product relationship (that is, the quinoline type is derived from the indole type in a one-step reaction). 

Amino acids are the structural units of protein, and some of them have been used as drugs or food additives, so the determination of amino acids is useful for biochemical research and for commercial product analysis. Among essential amino acids, there are three aromatic amino acids, phenylalanine, tyrosine and tryptophan, which exhibit fluorescence when they are excited by ultraviolet rays. So it is possible to determine them by the fluorescence spectroscopic method. The A ax of phenylalanine, tyrosine and tryptophan are 282 nm, 303 nm and 348 nm respectively, but their fluorescence spectra are partially overlapped. Since the separation operation of these three amino acids is tedious and... 

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