7423-92-9Relevant articles and documents
Spectrophotometric Studies of the Copper(II)-D-o-Tyrosine Complex. Assignment of the 330-nm Dichroic Band in Copper(II) and Iron(III) Transferrins
Garnier-Suillerot, Arlette,Albertini, Jean-Paul,Collet, Andre,Faury, Liliane,Pastor, Jose-Maria,Tosi, Lucia
, p. 2544 - 2549 (1981)
The separation of both enantiomers of racemic o-tyrosine by means of binaphthylphosphoric acid has been undertaken.Copper(II) interacts with D-o-tyrosine to form two complexes.The first, obtained at pH 6, diplays a circular-dichroism (c.d.) spectral pattern characteristic of metal co-ordination through amino-nitrogens and carboxylate oxygens.The second complex starts to form at pH 8 and is fully defined at pH 10.5.Its c.d.spectrum, in the region below 400 nm, is very similar to those of iron(III) and copper(II) transferrins and displays two well defined bands at ca. 400 and 330 nm.So far, only the origin of the higher-frequency peak has been well established ar arising from a phenolate-oxygen-to-metal charge-transfer transition, whereas that of the lower-frequency peak remains uncertain.Resonance-Raman measurements upon excitation into the envelope of the two absorptions at 400 and 330 nm clearly indicate a common origin to both bands, namely: phenolate oxygen -> Cu(II) charge-transfer transition.
One-Pot Enzymatic Synthesis of d-Arylalanines Using Phenylalanine Ammonia Lyase and l-Amino Acid Deaminase
Zhu, Longbao,Feng, Guoqiang,Ge, Fei,Song, Ping,Wang, Taotao,Liu, Yi,Tao, Yugui,Zhou, Zhemin
, p. 1 - 15 (2018/06/11)
The phenylalanine ammonia-lyase (AvPAL) from Anabaena variabilis catalyzes the amination of substituent trans-cinnamic acid (t-CA) to produce racemic d,l-enantiomer arylalanine mixture owing to its low stereoselectivity. To produce high optically pure d-arylalanine, a modified AvPAL with high d-selectivity is expected. Based on the analyses of catalytic mechanism and structure, the Asn347 residue in the active site was proposed to control stereoselectivity. Therefore, Asn347 was mutated to construct mutant AvPAL-N347A, the stereoselectivity of AvPAL-N347A for d-enantiomer arylalanine was 2.3-fold higher than that of wild-type AvPAL (WtPAL). Furthermore, the residual l-enantiomer product in reaction solution could be converted into the d-enantiomer product through stereoselective oxidation by PmLAAD and nonselective reduction by reducing agent NH3BH3. At optimal conditions, the conversion rate of t-CA and optical purity (enantiomeric excess (eeD)) of d-phenylalanine reached 82% and exceeded 99%, respectively. The two enzymes displayed activity toward a broad range of substrate and could be used to efficiently synthesize d-arylalanine with different groups on the phenyl ring. Among these d-arylalanines, the yield of m-nitro-d-phenylalanine was highest and reached 96%, and the eeD exceeded 99%. This one-pot synthesis using AvPAL and PmLAAD has prospects for industrial application.
Kinetic of adsorption and of photocatalytic degradation of phenylalanine effect of pH and light intensity
Elsellami,Vocanson,Dappozze,Puzenat,Pa?sse,Houas,Guillard
experimental part, p. 142 - 148 (2011/10/12)
Phenylalanine (Phe) was chosen to study the TiO2 photocatalytic degradation of amino acids, which are at the origin of the formation of odorous compounds after chlorination. The photocatalytic degradation has been investigated in aqueous solutions containing TiO2 suspensions as photocatalyst, in order to assess the influence of various parameters, such as adsorption, initial concentration, pH and radiant flux on the photocatalytic process. Results showed no correlation between dark adsorption and photocatalytic degradation. A multilayer kinetic was observed in the dark with a monolayer corresponding to less that 1% of OH covered, whereas Langmuir-Hinshelwood model seems to modelize the photocatalytic disappearance of Phe. However, even if the form of the curve is similar to L-H model, the degradation of phenylalanine is not a kinetic of L-H as we could plan it by considering the adsorption of the phenylalanine in the dark. The study of the mineralization of carbon and nitrogen showed that nitrogen atoms were predominantly photoconverted into NH4+ and a total mineralization of nitrogen and carbon seems occur. The identification of the by-products by LC-MS reveal mono- and di-hydroxylation and nitrogen-carbon (N-C) cleavage. The effect of pH showed an increase of adsorption under acid pH but a decrease of disappearance rate. The more efficient degradation was found at basic pH. The evolution of hydroxylated compounds of phenylalanine as a function of conversion revealed the presence of more hydroxylated compounds at natural pH and at basic pH compared to acid pH suggesting a modification of mechanism with solution pH. The effect of the radiant flux evaluated under different initial concentration of phenylalanine allowed us to determine that Κ increases by increasing the radiant flux, whereas Κ decreases or remains constant from about a value of 3.5 mW/cm2. The disappearance rate as a function of radiant flux has been showed to reach a maximal value corresponding to a maximal quantum yield of 1.6%.
Perthamides C and D, two new potent anti-inflammatory cyclopeptides from a Solomon Lithistid sponge Theonella swinhoei
Festa, Carmen,De Marino, Simona,Sepe, Valentina,Monti, Maria Chiara,Luciano, Paolo,D'Auria, Maria Valeria,Débitus, Cecile,Bucci, Mariarosaria,Vellecco, Valentina,Zampella, Angela
experimental part, p. 10424 - 10429 (2010/03/04)
Two new metabolites, perthamides C and D, have been isolated from the marine sponge Theonella swinhoei. Their structures were determined by interpretation of NMR and ESIMS data. All compounds exhibited in vivo potent anti-inflammatory activity. Biological
PROTEIN MODIFIER PRODUCTION INHIBITOR
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Page/Page column 19; 31-32, (2008/06/13)
[PLOBLEMS] To provide a inhibitor of protein modification products formation capable of inhibiting of vitamin B6 deficiency disease as a side effect, especially a renal protective agent. [MEANS FOR SOLVING PROBLEMS] There is provided a use, as an active ingredient, of any of free or salt-form compounds of either of the formulae: (I) (II) [wherein R1 is substituted or unsubstituted aromatic ring; and each of R2, R3 and R4 is a hydrogen atom or monovalent organic group, or alternatively R2 and R3 cooperate to form a condensed ring or R3 and R4 cooperate to represent a divalent organic group, provided that R3 and R4 are not simulataneously hydrogen atoms].
Formation of a hydroxyl radical from riboflavin sodium phosphate by photo-illumination
Ishimitsu, Susumu,Mishima, Ikuko,Tsuji, Sumiko,Shibata, Tadashi
, p. 2107 - 2109 (2007/10/03)
Photo-illumination of riboflavin sodium phosphate (Rp) with phenylalanine produced significant levels of o-tyrosine, m-tyrosine and p- tyrosine as hydroxylated products. The hydroxylation of Rp was pH-dependent, and the maximum rate was around pH 4.5. Replacement of air with nitrogen prevented the formation of tyrosine isomers while the addition of superoxide dismutase or catalase to this system prevented hydroxylation. The tyrosine formation by the system was significantly prevented by hydroxyl radical (HO·) scavengers such as potassium iodide, potassium bromide, thiourea and sodium formate. No free iron and cupric ions were detected in the reaction mixture by inductively-coupled plasma atomic emission spectrometry. The above results suggest that the formation of HO· may occur in the photochemical reaction system in the presence of Rp under aerobic conditions, and that a superoxide radical and hydrogen peroxide may be involved in HO· formation.
Synthesis of chirally pure 2,5-disubstituted diketopiperazines derived from trisubstituted phenylalanines
Danthi, Satyavijayan Narasimhan,Hill, Ronald A.
, p. 835 - 844 (2007/10/03)
Some new chirally pure 2,5-substituted diketopiperazines were synthesized starting from 2-methoxybenzyl alcohol. This multistep synthesis proceeds through the enzymatic synthesis of chirally pure amino acids, protection and dipeptide coupling, cyclization of dipeptide ester formates, and nitration of the resulting diketopiperazines.
Formation of a hydroxyl radical from tar dye by photo-illumination
Ishimitsu,Ohmori,Tsuji,Shibata
, p. 1810 - 1812 (2007/10/03)
When indigo carmine (B-2) was illuminated in the presence of phenylalanine in 0.1 M citrate buffer (pH 4.0), p-tyrosine, m-tyrosine and o-tyrosine were identified as hydroxylated products. However, ten other food colors did not form tyrosine isomers. The hydroxylation of B-2 was pH-dependent, and the maximum rate was found at around pH 4.0. Replacement of air with nitrogen gas completely prevented the formation of tyrosine isomers and the decomposition of B-2. In contrast, oxygen gas accelerated both the hydroxylation and the decomposition. The addition of superoxide dismutase or catalase to this system prevented hydroxylation. Chemical scavengers of the hydroxyl radical (HO·) prevented the hydroxylation. On the other hand, a singlet oxygen scavenger had no significant effect. The above results suggest that the formation of HO· may occur in the photochemical reaction system in the presence of B-2 under aerobic conditions, and that a superoxide radical and hydrogen peroxide may he involved in the HO· formation.
Phenylalanine: Its *OH and SO4(1-*)-Induced Oxidation and Decarboxylation. A Pulse Radiolysis and Product Analysis Study
Wang, Degui,Schuchmann, Heinz-Peter,Sonntag, Clemens von
, p. 761 - 770 (2007/10/02)
Phenylalanine has been oxidized by radiolytically generated hydroxyl and sulfate radicals, the ensuing intermediates and their reactions have been studied by pulse radiolysis and product analysis in the absence and presence of oxidants such as Fe(CN)6(3-) and O2.Upon OH radical attack, hydroxycyclohexadienyl-type radicals are mainly formed while H-abstraction reactions can be neglected.In the presence of Fe(CN)6(3-) these radicals are for the most part oxidized to the corresponding tyrosines (80percent), except for the ipso-OH-adduct radicals (ca. 20percent=.It is concluded that *OH-addition is almost random, but with a slight avoidance of the meta-position relative to the ortho-, para- and ipso-positions.Oxygen adds reversibly to the OH-adduct radicals (kf = 1.8x108 dm3 mol-1 s-1, kr = 5.4x104 s-1).In this case, tyrosine formation occurs by HO2*-elimination.However, due to side reactions, tyrosine formation only reaches 52percent of the OH radical yield.The tyrosine yield drops to 10percent in the absence of an oxidant.Upon SO4(1-*)-attack, decarboxylation becomes a major process (33percent of SO4(1-*) alongside the production of tyrosines (43percent).Here, with Fe(CN)6(3-) as the oxidant the formation of p-Tyr (18.5percent) and m-Tyr (16.5percent) is preferred over o-Tyr formation (8.5percent).It is believed that in analogy to other systems a radical cation is formed immediately upon SO4(1-*)-attack which either reacts with water under the formation of hydroxycyclohexadienyl-type ("OH-adduct") radicals, or decarboxylates after intramolecular electron transfer.The radical cation can also arise indirectly through H(1+)-calalysed water elimination from the *OH-adduct radicals.At pH 2 and a dose rate of 0.0046 Gy s-1 CO2 formation matches the OH radical yield when *OH is the attacking radical.Below pH 2, G(CO2) decreases with falling pH.This indicates the occurrence of another, unimolecular, pathway under these conditions competing effectively with decarboxylation.This appears to be a relatively slow deprotonation reaction of the carboxyl-protonated phenylalanine radical cation which gives rise to the benzyl-type radical. Key words: Amino acid; phenylalanine; pulse radiolysis; peroxy radicals; sulfate radical.
OXIDATION OF L-PHENYLALANINE BY THE MODIFIED UDENFRIEND SYSTEM
Blanchard, M.,Bouchoule, C.,Djaneye-Boundjou, G.,Canesson, P.
, p. 2177 - 2178 (2007/10/02)
L-phenylalanine is oxidized by oxygen into 3,4-dihydroxyphenylalanine (DOPA) at 40 deg C with Fe(2+) EDTA as a catalyst.For the reduction of Fe(3+) species, electrons are released from the cathode of an electrochemical cell.
