scholarly journals Formation of N′-formylkynurenine in proteins from lens and other sources by exposure to sunlight

1971 ◽  
Vol 125 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Antoinette Pirie
Keyword(s):  
Indole Ring ◽  
Lens Proteins ◽  
Free Tryptophan ◽  
Tryptophan Residues ◽  
Oxidative Change ◽  
Oxidative Effect

The photo-oxidative effect of sunlight on the tryptophan residues of proteins and on free tryptophan is described. Evidence is presented that the indole ring is split to yield N′-formylkynurenine. The possible relation of this photo-oxidative change to changes in the lens proteins of brown cataracts is discussed.

Packing of aromatic rings against tryptophan residues in proteins

1999 ◽  
Vol 55 (8) ◽  
pp. 1421-1427 ◽  
Author(s):  
Uttamkumar Samanta ◽  
Debnath Pal ◽  
Pinak Chakrabarti
Keyword(s):  
Protein Data Bank ◽  
Chemical Nature ◽  
Data Bank ◽  
Side Chains ◽  
Indole Ring ◽  
Aromatic Rings ◽  
Dominant Feature ◽  
Tryptophan Residues ◽  
Uniform Manner ◽  
Aromatic Side Chains

The geometry of the interaction of the aromatic side chains of phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp) and histidine (His) with the indole ring of Trp has been analyzed using the structures in the Protein Data Bank in order to understand the dependence of the packing behaviour on the size and chemical nature of the aromatic rings. The Phe ring prefers to interact either perpendicularly, with its edge pointing towards the Trp face, or in an offset-stacked arrangement. The edge-to-face motif is typical of a Trp–Trp pair. While parallel stacking is the dominant feature of Trp–His interaction, Tyr packs in a more uniform manner around Trp with a higher than expected occurrence at the edge and a few cases of possible OH–π interaction.

Rearrangements in the mechanisms of the indole alkaloid prenyltransferases

2013 ◽  
Vol 85 (10) ◽  
pp. 1935-1948 ◽  
Author(s):  
Niusha Mahmoodi ◽  
Qi Qian ◽  
Louis Y. P. Luk ◽  
Martin E. Tanner
Keyword(s):  
Indole Alkaloid ◽  
Ion Pair ◽  
Pair Formation ◽  
Tryptophan Residue ◽  
Cope Rearrangement ◽  
Indole Ring ◽  
Structural Homology ◽  
Dimethylallyl Diphosphate ◽  
Free Tryptophan ◽  
Dimethylallyltryptophan Synthase

The indole prenyltransferases are a family of metal-independent enzymes that catalyze the transfer of a prenyl group from dimethylallyl diphosphate (DMAPP) onto the indole ring of a tryptophan residue. These enzymes are remarkable in their ability to direct the prenyl group in either a “normal” or “reverse” fashion to positions with markedly different nucleophilicity. The enzyme 4-dimethylallyltryptophan synthase (4-DMATS) prenylates the non-nucleophilic C-4 position of the indole ring in free tryptophan. Evidence is presented in support of a mechanism that involves initial ion pair formation followed by a reverse prenylation at the nucleophilic C-3 position. A Cope rearrangement then generates the C-4 normal prenylated intermediate and deprotonation rearomatizes the indole ring. The enzyme tryprostatin B synthase (FtmPT1) catalyzes the normal C-2 prenylation of the indole ring in brevianamide F (cyclo-L-Trp-L-Pro). It shares high structural homology with 4-DMATS, and evidence is presented in favor of an initial C-3 prenylation (either normal or reverse) followed by carbocation rearrangements to give product. The concept of a common intermediate that partitions to different products via rearrangements can help to explain how these evolutionarily related enzymes can prenylate different positions on the indole ring.

Enzymatic derivatizations of tryptophan residues in peptides and proteins, free tryptophan, and its metabolites with tryptophan side chain oxidase types I and II from Pseudomonas

Amino Acids ◽  
1990 ◽  
pp. 1059-1066
Author(s):  
Eiko Nakamaru ◽  
Takaaki Kawashima ◽  
Yoshiki Kamiyama ◽  
Hidefumi Yoshii ◽  
Akira Kanda ◽  
...  
Keyword(s):  
Side Chain ◽  
Free Tryptophan ◽  
Tryptophan Residues

Direct Photometric Determination of Globulin in Serum

1971 ◽  
Vol 17 (5) ◽  
pp. 358-362 ◽  
Author(s):  
Harry Goldenberg ◽  
Patricia A Drewes
Keyword(s):  
Glyoxylic Acid ◽  
Photometric Determination ◽  
Confidence Limits ◽  
Serum Globulin ◽  
Clin Pathol ◽  
Free Tryptophan ◽  
Tryptophan Residues ◽  
Fractionation Method ◽  
Salt Fractionation

Abstract A convenient method for direct photometric determination of total globulin in serum has been developed using a one-tube, one-reagent system. The analysis is based on a variation of the Hopkins-Cole reaction, in which glyoxylic acid condenses with the tryptophan residues present in globulin to produce a purple color. In the presence of copper and under the conditions of the analysis, color intensity is proportional to serum globulin concentration. The method is standardized with either a serum control or a suitable tryptophan derivative (e.g., acetyl-DL-tryptophan). There is little or no interference from free tryptophan, albumin, bilirubin, lipemia, or mild hemolysis. The precision of the method is ±3% (95% confidence limits), and results agree with those obtained by the salt fractionation method of Wolfson et al. [Amer. J. Clin. Pathol. 18, 723 (1948)]: t = -0.88; critical t = 2.02; 95% confidence limits.

Free tryptophan residues inhibit quorum sensing of Pseudomonas aeruginosa: a potential approach to inhibit the development of microbial biofilm

2018 ◽  
Vol 200 (10) ◽  
pp. 1419-1425 ◽  
Author(s):  
Poulomi Chakraborty ◽  
Akshay Vishnu Daware ◽  
Monika Kumari ◽  
Ahana Chatterjee ◽  
Disha Bhattacharyya ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Microbial Biofilm ◽  
Potential Approach ◽  
Free Tryptophan ◽  
Tryptophan Residues
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