- The retro-mannich cleavage of δ1,δ1'-tryptophan dimers
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Under acidic conditions tryptophan sidechains crosslink to form δ1, δ1'-tryptophan dimers through a Mannich-type mechanism. Tryptophan dimers are readily cleaved at high temperatures under acidic conditions making it impossible to isolate tryptophan dimers under standard conditions of acidic protein hydrolysis. In a prescriptive sense this cleavage can be used to recover peptides that have undergone tryptophan crosslinking, although the yields drop with increasing peptide length due to competitive cleavage of the amide bonds. The best conditions for cleavage involve heating the dimeric peptides in dilute ethanolic HCl at 150°C in the presence of ten equivalents of ethanedithiol. Copyright (C) 1998 Elsevier Science Ltd.
- Biggs, Bluegrass,Presley, Alice L.,Van Vranken, David L.
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- SYNTHESIS OF AROMATIC AMINO ACID ETHYL ESTERS BY α-CHYMOTRYPSIN IN SOLUTIONS OF HIGH ETHANOL CONCENTRATIONS
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N-Acetyl-L-tryptophan and N-acetyl-L-tyrosine were converted to their ethyl esters by α-chymotrypsin in water-ethanol mixed solvents with ethanol concentration higher than 90percent.The effects of the solvent composition and the stability of α-chymotrypsin in these solutions are described.
- Kise, Hideo,Shirato, Hitoshi
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- USE OF ESTER DERIVATIVE OF TRYPTOPHAN AS DEODORANT AND/OR PERFUME AGENT
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This invention relates to the use of at least one following compound having formula (I), as well as the salts thereof, the optical and geometric isomers thereof, and the solvates thereof, as deodorant agent for treating body odor, preferably underarm odor:
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- Ketoprofen-induced formation of amino acid photoadducts: Possible explanation for photocontact allergy to ketoprofen
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Photocontact allergy is a well-known side effect of topical preparations of the nonsteroidal anti-inflammatory drug ketoprofen. Photocontact allergy to ketoprofen appears to induce a large number of photocross allergies to both structurally similar and structurally unrelated compounds. Contact and photocontact allergies are explained by structural modification of skin proteins by the allergen. This complex is recognized by the immune system, which initiates an immune response. We have studied ketoprofen's interaction with amino acids to better understand ketoprofen's photoallergenic ability. Irradiation of ketoprofen and amino acid analogues resulted in four different ketoprofen photodecarboxylation products (6-9) together with a fifth photoproduct (5). Dihydroquinazoline 5 was shown to be a reaction product between the indole moiety of 3-methylindole (Trp analogue) and the primary amine benzylamine (Lys analogue). In presence of air, dihydroquinazoline 5 quickly degrades into stable quinazolinone 12. The corresponding quinazolinone (17) was formed upon irradiation of ketoprofen and the amino acids N-acetyl-l-Trp ethyl ester and l-Lys ethyl ester. The formation of these models of an immunogenic complex starts with the ketoprofen-sensitized formation of singlet oxygen, which reacts with the indole moiety of Trp. The formed intermediate subsequently reacts with the primary amino functionality of Lys, or its analogue, to form a Trp-Lys adduct or a mimic thereof. The formation of a specific immunogenic complex that does not contain the allergen but that can still induce photocontact allergy would explain the large number of photocross allergies with ketoprofen. These allergens do not have to be structurally similar as long as they can generate singlet oxygen. To the best of our knowledge, there is no other suggested explanation for ketoprofen's photoallergenic properties that can account for the observed photocross allergies. The formation of a specific immunogenic complex that does not contain the allergen is a novel hypothesis in the field of contact and photocontact allergy.
- Karlsson, Isabella,Persson, Elin,Ekebergh, Andreas,M?rtensson, Jerker,B?rje, Anna
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p. 1294 - 1303
(2014/08/05)
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- Resolution of N-protected amino acid esters using whole cells of Candida parapsilosis ATCC 7330
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Whole cells of Candida parapsilosis ATCC 7330 were used for the resolution of N-acetyl amino acid esters. Excellent enantioselectivities (E = 40 to >500) were achieved for the resolution of N-protected protein and non-protein amino acid esters giving good yields (28-50%) and high enantiomeric excesses (up to >99%) for both enantiomers.
- Stella, Selvaraj,Chadha, Anju
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experimental part
p. 457 - 460
(2010/06/21)
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- Crosslinking of imprinted proteases to maintain a tailor-made substrate selectivity in aqueous solutions
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A covalent method to keep imprinted properties of proteins stable in aqueous as well as in organic environment is described. To stabilize the ligand induced acceptance for d-configured substrates by α-chymotrypsin or subtilisin Carlsberg, each protein was first vinylated by acylation with itaconic anhydride. Then, the tailoring of the derivatized proteins by precipitation in the presence of N-acetyl-D-tryptophan from an aqueous medium with 1-propanol, and the subsequent crosslinking of the enzyme preparations with ethylene glycol dimethacrylate in cyclohexane was carried out. The crosslinked imprinted proteins (CLIPs) obtained catalyzed the hydrolysis of N-acetyl-D-tryptophan ethyl ester in phosphate buffer and the corresponding back reaction in cyclohexane, respectively. The repeated use of CLIP-α- chymotrypsin in D-ester hydrolysis was demonstrated. Furthermore, this particular CLIP-α-chymotrypsin showed no loss in activity when it subsequently was used in the synthesis of N-acetyl-D-tryptophan ethyl ester in cyclohexane again. In the case of D-ester hydrolysis the reaction rate acceleration (k(enz)/k(nonenz)) was in the same order of magnitude of about 104 -105 mM-1 for the two CLIP-proteases. The results suggest that enzymes tailored by imprinting technique do not lose their induced 'new' property in the presence of water when they are prepared according to the described vinylation/crosslinking method (CLIP technique).
- Peissker, Fabian,Fischer, Lutz
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p. 2231 - 2237
(2007/10/03)
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- Accelerated esterification of aminoacids with lipoglycosylated α-chymotrypsin in polar solvents
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A lipodisaccharide possessing a reactive aldopentose function, the 6-O-octyl-β-D-galactopyranosyl-(1→5)-L-arabinose (5), has been prepared. The reductive alkylation of four of the lysine residues of the bovine α-chymotrypsin led to a lipo-1-deoxyglycytolated enzyme. This modified protein efficiently catalyzed the synthesis of N-acetyl aminoacid ethyl esters in different solvents with 2.5-3% water contents. Compared to the native enzyme, enhanced esterification rates were determined, particularly in tetrahydrofuran, ethyl acetate and acetonitrile.
- Cabaret, Daniel,Maillot, Sophie,Wakselman, Michel
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p. 2131 - 2134
(2007/10/02)
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- Dehydrogenation of Indolines to Indoles via Azasulphonium Salts or N-Chloramines
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The dehydrogenation of indolines to indoles without using mineral oxidising reagents is described.The conversion was achieved via either azasulphonium salts or N-chloramines, the former route involving milder conditions but a more complex procedure.
- Kawase, Masami,Miyake, Yuko,Kikugawa, Yasuo
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p. 1401 - 1404
(2007/10/02)
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- A NEW DEHYDROGENATION REACTION OF INDOLINES TO INDOLES VIA AZASULFONIUM SALTS
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Indolines (1) have been converted to the corresponding azasulfonium salts (2) and the subsequent intramolecular base catalyzed abstraction of the hydrogen at C-2 gave indoles (4) in good yields.
- Kikugawa, Yasuo,Kawase, Masami
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p. 445 - 446
(2007/10/02)
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