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A novel phenylalanine ammonia-lyase from Pseudozyma antarctica for stereoselective biotransformations of unnatural amino acids
A novel phenylalanine ammonia-lyase of the psychrophilic yeast Pseudozyma antarctica (PzaPAL) was identified by screening microbial genomes against known PAL sequences. PzaPAL has a significantly different substrate binding pocket with an extended loop (26 aa long) connected to the aromatic ring binding region of the active site as compared to the known PALs from eukaryotes. The general properties of recombinant PzaPAL expressed in E. coli were characterized including kinetic features of this novel PAL with L-phenylalanine (S)-1a and further racemic substituted phenylalanines rac-1b-g,k. In most cases, PzaPAL revealed significantly higher turnover numbers than the PAL from Petroselinum crispum (PcPAL). Finally, the biocatalytic performance of PzaPAL and PcPAL was compared in the kinetic resolutions of racemic phenylalanine derivatives (rac-1a-s) by enzymatic ammonia elimination and also in the enantiotope selective ammonia addition reactions to cinnamic acid derivatives (2a-s). The enantiotope selectivity of PzaPAL with o-, m-, p-fluoro-, o-, p-chloro- and o-, m-bromo-substituted cinnamic acids proved to be higher than that of PcPAL.
Varga, Andrea,Csuka, Pál,Sonesouphap, Orlavanah,Bánóczi, Gergely,To?a, Monica Ioana,Katona, Gabriel,Molnár, Zsófia,Bencze, László Csaba,Poppe, László,Paizs, Csaba
p. 185 - 194
(2020/04/28)

Bi-enzymatic Conversion of Cinnamic Acids to 2-Arylethylamines
The conversion of carboxylic acids, such as acrylic acids, to amines is a transformation that remains challenging in synthetic organic chemistry. Despite the ubiquity of similar moieties in natural metabolic pathways, biocatalytic routes seem to have been overlooked for this purpose. Herein we present the conception and optimisation of a two-enzyme system, allowing the synthesis of β-phenylethylamine derivatives from readily-available ring-substituted cinnamic acids. After characterisation of both parts of the reaction in a two-step approach, a set of conditions allowing the one-pot biotransformation was optimised. This combination of a reversible deaminating and irreversible decarboxylating enzyme, both specific for the amino acid intermediate in tandem, represents a general method by which new strategies for the conversion of carboxylic acids to amines could be designed.
Weise, Nicholas J.,Thapa, Prasansa,Ahmed, Syed T.,Heath, Rachel S.,Parmeggiani, Fabio,Turner, Nicholas J.,Flitsch, Sabine L.
p. 995 - 998
(2020/01/21)

Highly selective synthesis of d-amino acids from readily available l-amino acids by a one-pot biocatalytic stereoinversion cascade
d-Amino acids are key intermediates required for the synthesis of important pharmaceuticals. However, establishing a universal enzymatic method for the general synthesis of d-amino acids from cheap and readily available precursors with few by-products is challenging. In this study, we constructed and optimized a cascade enzymatic route involving l-amino acid deaminase and d-amino acid dehydrogenase for the biocatalytic stereoinversions of l-amino acids into d-amino acids. Using l-phenylalanine (l-Phe) as a model substrate, this artificial biocatalytic cascade stereoinversion route first deaminates l-Phe to phenylpyruvic acid (PPA) through catalysis involving recombinant Escherichia coli cells that express l-amino acid deaminase from Proteus mirabilis (PmLAAD), followed by stereoselective reductive amination with recombinant meso-diaminopimelate dehydrogenase from Symbiobacterium thermophilum (StDAPDH) to produce d-phenylalanine (d-Phe). By incorporating a formate dehydrogenase-based NADPH-recycling system, d-Phe was obtained in quantitative yield with an enantiomeric excess greater than 99%. In addition, the cascade reaction system was also used to stereoinvert a variety of aromatic and aliphatic l-amino acids to the corresponding d-amino acids by combining the PmLAAD whole-cell biocatalyst with the StDAPDH variant. Hence, this method represents a concise and efficient route for the asymmetric synthesis of d-amino acids from the corresponding l-amino acids.
Zhang, Danping,Jing, Xiaoran,Zhang, Wenli,Nie, Yao,Xu, Yan
p. 29927 - 29935
(2019/10/01)

Engineered Aminotransferase for the Production of d-Phenylalanine Derivatives Using Biocatalytic Cascades
d-Phenylalanine derivatives are valuable chiral building blocks for a wide range of pharmaceuticals. Here, we developed stereoinversion and deracemization biocatalytic cascades to synthesize d-phenylalanine derivatives that contain electron-donating or -withdrawing substituents of various sizes and at different positions on the phenyl ring with a high enantiomeric excess (90 to >99 % ee) from commercially available racemic mixtures or l-amino acids. These whole-cell systems couple Proteus mirabilis l-amino acid deaminase with an engineered aminotransferase that displays native-like activity towards d-phenylalanine, which we generated from Bacillus sp. YM-1 d-amino acid aminotransferase. Our cascades are applicable to preparative-scale synthesis and do not require cofactor-regeneration systems or chemical reducing agents.
Walton, Curtis J. W.,Parmeggiani, Fabio,Barber, Janet E. B.,McCann, Jenna L.,Turner, Nicholas J.,Chica, Roberto A.
p. 470 - 474
(2017/12/15)

Kinetic Resolution of Aromatic β-Amino Acids Using a Combination of Phenylalanine Ammonia Lyase and Aminomutase Biocatalysts
An enzymatic strategy for the preparation of (R)-β-arylalanines employing phenylalanine aminomutase and ammonia lyase (PAM and PAL) enzymes has been demonstrated. Candidate PAMs with the desired (S)-selectivity from Streptomyces maritimus (EncP) and Bacillus sp. (PabH) were identified via sequence analysis using a well-studied template sequence. The newly discovered PabH could be linked to the first ever proposed biosynthesis of pyloricidin-like secondary metabolites and was shown to display better β-lyase activity in many cases. In spite of this, a method combining the higher conversion of EncP with a strict α-lyase from Anabaena variabilis (AvPAL) was found to be more amenable, allowing kinetic resolution of five racemic substrates and a preparative-scale reaction with >98% (R) enantiomeric excess. This work represents an improved and enantiocomplementary method to existing biocatalytic strategies, allowing simple product separation and modular telescopic combination with a preceding chemical step using an achiral aldehyde as starting material. (Figure presented.).
Weise, Nicholas J.,Ahmed, Syed T.,Parmeggiani, Fabio,Turner, Nicholas J.
p. 1570 - 1576
(2017/05/05)

Telescopic one-pot condensation-hydroamination strategy for the synthesis of optically pure L-phenylalanines from benzaldehydes
A chemo-enzymatic telescopic approach was designed for the synthesis of L-arylalanines in high yield and optical purity, starting from commercially available and inexpensive substituted benzaldehydes. The method exploits a chemical Knoevenagel–Doebner condensation (optimised to give complete conversions in a short reaction time, employing microwave irradiation) and a biocatalytic phenylalanine ammonia lyase mediated hydroamination (for the stereoselective addition of ammonia). The two reactions can be run sequentially in one pot, bringing together the advantages of chemical and biological catalysis. The preparative applicability was demonstrated with the synthesis of five L-dihalophenylalanines (71–84% yield, 98–99% ee) of relevance as molecular probes, for medicinal chemistry and for the synthesis of pharmaceutical ingredients.
Parmeggiani, Fabio,Ahmed, Syed T.,Weise, Nicholas J.,Turner, Nicholas J.
p. 7256 - 7262
(2016/10/26)

Single-Biocatalyst Synthesis of Enantiopure d-Arylalanines Exploiting an Engineered d-Amino Acid Dehydrogenase
A practical and efficient biocatalytic synthesis of aromatic d-amino acids has been developed, based on the reductive amination of the corresponding α-keto acids via a recombinant whole cell system composed of an engineered dehydrogenase and cofactor recycling apparatus. The reaction was shown to give excellent enantioselectivity (≥98%) and good yields at the preparative scale across a broad range of substrates. Additionally, the structure of the variant enzyme was solved to allow rationalisation of the observed reaction rates. The engineered whole cell catalyst was also used to mediate the production of d-phenylalanine derivatives from racemic mixtures and cheaper l-amino acids by combining it with an enantiocomplementary deaminase. (Figure presented.).
Parmeggiani, Fabio,Ahmed, Syed T.,Thompson, Matthew P.,Weise, Nicholas J.,Galman, James L.,Gahloth, Deepankar,Dunstan, Mark S.,Leys, David,Turner, Nicholas J.
p. 3298 - 3306
(2016/10/20)

Influence of the aromatic moiety in α- And β-arylalanines on their biotransformation with phenylalanine 2,3-aminomutase from: Pantoea agglomerans
In this study enantiomer selective isomerization of various racemic α- and β-arylalanines catalysed by phenylalanine 2,3-aminomutase from Pantoea agglomerans (PaPAM) was investigated. Both α- and β-arylalanines were accepted as substrates when the aryl moiety was relatively small, like phenyl, 2-, 3-, 4-fluorophenyl or thiophen-2-yl. While 2-substituted α-phenylalanines bearing bulky electron withdrawing substituents did not react, the corresponding substituted β-aryl analogues were converted rapidly. Conversion of 3- and 4-substituted α-arylalanines happened smoothly, while conversion of the corresponding β-arylalanines was poor or non-existent. In the range of pH 7-9 there was no significant influence on the conversion of racemic α- or β-(thiophen-2-yl)alanines, whereas increasing the concentration of ammonia (ammonium carbonate from 50 to 1000 mM) inhibited the isomerization progressively and decreased the amount of the by-product (i.e. (E)-3-(thiophen-2-yl)acrylic acid was detected). In all cases, the high ee values of the products indicated excellent enantiomer selectivity and stereospecificity of the isomerization except for (S)-2-nitro-α-phenylalanine (ee 92%) from the β-isomer. Substituent effects were rationalized by computational modelling revealing that one of the main factors controlling biocatalytic activity was the energy difference between the covalent regioisomeric enzyme-substrate complexes.
Varga, Andrea,Bánóczi, Gergely,Nagy, Botond,Bencze, László Csaba,To?a, Monica Ioana,Gellért, ákos,Irimie, Florin Dan,Rétey, János,Poppe, László,Paizs, Csaba
p. 56412 - 56420
(2016/07/06)

Intensified biocatalytic production of enantiomerically pure halophenylalanines from acrylic acids using ammonium carbamate as the ammonia source
An intensified, industrially-relevant strategy for the production of enantiopure halophenylalanines has been developed using the novel combination of a cyanobacterial phenylalanine ammonia lyase (PAL) and ammonium carbamate reaction buffer. The process boasts STYs up to >200 g L-1 d-1, ees ≥ 98% and simplified catalyst/reaction buffer preparation and work up.
Weise, Nicholas J.,Ahmed, Syed T.,Parmeggiani, Fabio,Siirola, Elina,Pushpanath, Ahir,Schell, Ursula,Turner, Nicholas J.
p. 4086 - 4089
(2016/07/06)

The bacterial ammonia lyase EncP: A tunable biocatalyst for the synthesis of unnatural amino acids
Enzymes of the class I lyase-like family catalyze the asymmetric addition of ammonia to arylacrylates, yielding high value amino acids as products. Recent examples include the use of phenylalanine ammonia lyases (PALs), either alone or as a gateway to deracemization cascades (giving (S)- or (R)-α-phenylalanine derivatives, respectively), and also eukaryotic phenylalanine aminomutases (PAMs) for the synthesis of the (R)-β-products. Herein, we present the investigation of another family member, EncP from Streptomyces maritimus, thereby expanding the biocatalytic toolbox and enabling the production of the missing (S)-β-isomer. EncP was found to convert a range of arylacrylates to a mixture of (S)-α- and (S)-β-arylalanines, with regioselectivity correlating to the strength of electron-withdrawing/-donating groups on the ring of each substrate. The low regioselectivity of the wild-type enzyme was addressed via structure-based rational design to generate three variants with altered preference for either α- or β-products. By examining various biocatalyst/substrate combinations, it was demonstrated that the amination pattern of the reaction could be tuned to achieve selectivities between 99:1 and 1:99 for β:α-product ratios as desired.
Weise, Nicholas J.,Parmeggiani, Fabio,Ahmed, Syed T.,Turner, Nicholas J.
supporting information
p. 12977 - 12983
(2015/10/28)

Phenylalanine ammonia lyase catalyzed synthesis of amino acids by an MIO-cofactor independent pathway
Phenylalanine ammonia lyases (PALs) belong to a family of 4-methylideneimidazole-5-one (MIO) cofactor dependent enzymes which are responsible for the conversion of L-phenylalanine into trans-cinnamic acid in eukaryotic and prokaryotic organisms. Under conditions of high ammonia concentration, this deamination reaction is reversible and hence there is considerable interest in the development of PALs as biocatalysts for the enantioselective synthesis of non-natural amino acids. Herein the discovery of a previously unobserved competing MIO-independent reaction pathway, which proceeds in a non-stereoselective manner and results in the generation of both L- and D-phenylalanine derivatives, is described. The mechanism of the MIO-independent pathway is explored through isotopic-labeling studies and mutagenesis of key active-site residues. The results obtained are consistent with amino acid deamination occurring by a stepwise E1cB elimination mechanism. All manner of things: A competing MIO-independent (MIO=4-methylideneimidazole-5-one) reaction pathway has been identified for phenylalanine ammonia lyases (PALs), which proceeds in a non-stereoselective manner, resulting in the generation of D-phenylalanine derivatives. The mechanism of D-amino acid formation is explored through isotopic-labeling studies and mutagenesis of key active-site residues.
Lovelock, Sarah L.,Lloyd, Richard C.,Turner, Nicholas J.
supporting information
p. 4652 - 4656
(2014/05/20)

Immunomodulatory peptides
The invention relates to peptides derivatized with a hydrophilic polymer which, in some embodiments, bind to human FcRn and inhibit binding of the Fc portion of an IgG to an FcRn, thereby modulating serum IgG levels. The disclosed compositions and methods may be used in some embodiments, for example, in treating autoimmune diseases and inflammatory disorders. The invention also relates, in further embodiments, to methods of using and methods of making the peptides of the invention.
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(2014/12/12)

Phenylalanine aminomutase-catalyzed addition of ammonia to substituted cinnamic acids: A route to enantiopure α- and β-amino acids
(Chemical Equation Presented) An approach is described for the synthesis of aromatic α- and β-amino acids that uses phenylalanine aminomutase to catalyze a highly enantioselective addition of ammonia to substituted cinnamic acids. The reaction has a broad scope and yields substituted α- and β-phenylalanines with excellent enantiomeric excess. The regioselectivity of the conversion is determined by substituents present at the aromatic ring. A box model for the enzyme active site is proposed, derived from the influence of the hydrophobicity of substituents on the enzyme affinity toward various substrates.
Szymanski, Wiktor,Wu, Bian,Weiner, Barbara,De Wildeman, Stefaan,Feringa, Ben L.,Janssen, Dick B.
supporting information; experimental part
p. 9152 - 9157
(2010/03/01)

Use of whole cell culture of Aeromonas sp. as enantioselective scavenger: A facile preparation of l-amino acid derivatives in high enantiomeric excess
The bacterium Aeromonas sp. (CGMCC 2226) can enantioselectively scavenge d-isomer, making l-amino acid derivatives (AADs) in high ee. The enantioselective scavenger (ES) has shown a broad substrate scope. Eleven l-AADs, Phe derivatives substituted with methyl-, mono- and dichloro-, bromo-, and nitro-group, were produced in high ee from corresponding racemates.
Zhang, Zizhang
experimental part
p. 1129 - 1131
(2009/09/04)

Enantioselective scavenging using homogenate of Rhodotorula graminis: a facile preparation of d-amino acid derivatives in enantiopure form
An enantioselective scavenger (ES) comprised homogenate of Rhodotorula graminis containing multiple enzymes can enantioselectively remove l-enantiomer in a racemic mixture of amino acid derivatives (AADs), yielding d-enantiomer in high ee. Thirteen non-proteinogenic AADs were produced in enantiopure d form. The method appears to be an efficient cleaning and preparative strategy which can be applied to the production of d-AADs in high ee by enantioselectively scavenging the 'l-contaminants'.
Zhang, Zizhang
body text
p. 6468 - 6470
(2009/04/06)

Process for the preparation of enantiomerically enriched indoline-2-carboxylic acid
The present invention relates to a process for the preparation of an enantiomerically enriched optionally substituted indoline-2-carboxylic acid or a salt thereof, said process comprising subjecting an enantiomerically enriched chiral 2-amino-3-(2-X-substituted aryl)-propionic acid or 2-yl-substituted-amino -3-(2-X-substituted aryl)-propionic acid or a salt thereof, wherein X is a leaving group, to cyclisation, preferably at a temperature of below about 140°C, and in case of the yl-substituted compound, removing said yl-substituent by hydrolysis either prior to or after said cyclisation.
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Page/Page column 17-18

(2008/06/13)

PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY ENRICHED INDOLINE-2-CARBOXYLIC ACID
The present invention relates to a process for the preparation of an enantiomerically enriched optionally substituted indoline-2-carboxylic acid or a salt thereof, wherein an enantiomerically enriched chiral ortho-X-substituted phenylalanine compound, wherein X is a leaving group, is subjected to cyclisation, preferably at a temperature of below about 140°C, upon formation of the enantiomerically enriched indoline-2-carboxylic acid compound.
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Page/Page column 30-31

(2008/06/13)

Resolution of non-protein amino acids via the microbial protease-catalyzed enantioselective hydrolysis of their N-unprotected esters
In the Aspergillus oryzae protease-catalyzed ester hydrolysis, substitution of N-unprotected amino acid esters for the corresponding N-protected amino acid esters resulted in a large enhancement of the hydrolysis rate, while the enantioselectivity was deteriorated strikingly when the substrates employed were the conventional methyl esters. This difficulty was overcome by employing esters bearing a longer alkyl chain such as the isobutyl ester. Utilizing this ester, amino acids carrying an aromatic side chain were resolved with excellent enantioselectivities (E=50 to >200). With amino acids bearing an aliphatic side chain also, good results in terms of the hydrolysis rate and enantioselectivity were obtained by employing such an ester as the isobutyl ester. Moreover, the enantioselectivity proved to be enhanced further by conducting the reaction at low temperature. This procedure was applicable to the case where the enantioselectivity was not high enough even by the use of the isobutyl ester.
Miyazawa, Toshifumi,Imagawa, Kiwamu,Minowa, Hiroe,Miyamoto, Toyoko,Yamada, Takashi
p. 10254 - 10261
(2007/10/03)

Enantioselective synthesis of non-natural amino acids using phenylalanine dehydrogenases modified by site-directed mutagenesis
The substrate scope of three mutants of phenylalanine dehydrogenase as biocatalysts for the transformation of a series of 2-oxo acids, structurally related to phenylpyruvic acid, to the analogous -amino acids, non-natural analogues of phenylalanine, has been investigated. The mutant enzymes are more tolerant than the wild type enzyme of the non-natural substrates, especially those with substituents at the 4-position on the phenyl ring. Excellent enantiocontrol resulted in all cases.
Busca, Patricia,Paradisi, Francesca,Moynihan, Eamonn,Maguire, Anita R.,Engel, Paul C.
p. 2684 - 2691
(2007/10/03)

Phenylalanine ammonia-lyase: The use of its broad substrate specificity for mechanistic investigations and biocatalysis - Synthesis of L-arylalanines
Several fluoro-and chlorophenylalanines were found to be good substrates of phenylalanine ammonialyase (PAL/EC 4.3.1.5) from parsley. The enantiomerically pure L-amino acids were obtained in good yields by reaction of the corresponding cinnamic acids with 5M ammonia solution (buffered to pH 10) in the presence of PAL. The kinetic constants for nine different fluoro-and chlorophenylalanines do not provide a rigorous proof for but are consistent with the previously proposed mechanism comprising an electrophilic attack of the methylidene-imidazolone cofactor of PAL at the aromatic nucleus as a first chemical step. In the resulting Friedel-Crafts-type σ complex the β-protons are activated for abstraction and consequently the pro-S is abstracted by an enzymic base. Results from semi-empirical calculations combined with a proposed partial active site model showed a correlation between the experimental kinetic constants and the change in polarization of the pro-S Cβ-H bond and heat of formation of the σ complexes, thus making the electrophilic attack at the neutral aromatic ring plausible. Furthermore, while 5-pyrimidinylalanine was found to be a moderately good substrate of PAL, 2-pyrimidinylalanine was an inhibitor.
Gloge, Andreas,Zon, Jerzy,Koevari, Agnes,Poppe, Laszlo,Retey, Janos
p. 3386 - 3390
(2007/10/03)

Enantioselective borane reduction of prochiral ketones catalyzed by a chloro-containing chiral β-amino alcohol
A chloro-containing chiral β-amino alcohol (S)-2-amino-3-(2-chlorophenyl)-1,1-diphenyl-1-propanol (1) was prepared from the related amino acid, which was synthesized via malonic ester method. As a catalyst for the enantioselective borane reduction of prochiral ketones, 1 is better than those that have a similar structure but have no halogen atom in the molecule.
Shen, Zong-Xuan,Lu, Jun,Zhang, Qing,Zhang, Ya-Wen
p. 2287 - 2289
(2007/10/03)

Resolution of non-protein amino acids via microbial protease-catalyzed ester hydrolysis: Marked enhancement of enantioselectivity by the use of esters with longer alkyl chains and at low temperature
In the microbial protease-catalyzed hydrolysis of amino acid esters with the free α-amino group, the enantioselectivity can be enhanced greatly by employing esters with longer alkyl chains such as the isobutyl ester instead of the conventional methyl ester and by conducting the reaction at low temperature.
Miyazawa, Toshifumi,Minowa, Hiroe,Miyamoto, Toyoko,Imagawa, Kiwamu,Yanagihara, Ryoji,Yamada, Takashi
p. 367 - 370
(2007/10/03)

Preparation of (R)-Phenylalanine Analogues by Enantioselective Destruction Using L-Amino Acid Oxidase
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Pirrung, Michael C.,Krishnamurthy, N.
p. 957 - 958
(2007/10/02)

METABOLISM OF D,L-CHLORO-PHENYLALANINES BY PHENYLALANINE AMINOTRANSFERASE ISOZYMES PURIFIED FROM BUSHBEAN SHOOTS
Key Word Index - Phaseolus vulgaris; Leguminosae; bushbean; metabolism; phenylalanine decarboxylase; phenylalanine aminotransferase; purification; substituted amino acids; D,L-chloro-phenylalanines.A series of mono-, di- and trichloro-D,L-phenylalanines was tested as substrates for both phenylalanine aminotransferase and phenylalanine decarboxylase partially purified from bushbean (Phaseolus vulgaris L.) seedling extracts by ammonium sulphate fractionation and Sephacryl S-300 gel filtration.While most of the D,L-chlorophenylalanines were transaminated at rates of 35-100percent of that observed with D,L-phenylalanine, no chloro-phenylalanine decarboxylase activity was observed.A transamination reaction is therefore likely to be the initial step in the conversion of chloro-phenylalanines to their corresponding chloro-phenylacetic acids via a reaction pathway similar to the known route for the metabolism of L-phenylalanine to phenylacetic acid.The highest specific activity of phenylalanine aminotransferase was found in both root and shoot tissues of bushbean at the 10-day stage of seedling growth.Partially purified extracts of these tissues were able to transaminate most of the mono- and dichloro-phenylalanines at ca 20-40percent of the rate observed with D,L-phenylalanine, while the trichloro-phenylalanines (assayed at lower concentrations due to solubility) were transaminated at rates equal to those observed with D,L-phenylalanine.The 4-chloro derivative was the best substrate tested showing rates of transamination that were 25percent higher than those observed with D,L-phenylalanine.Further purification of shoot fractions by DEAE-Sephacel chromatography resolved the phenylalanine aminotransferase activity into two peaks (enzymes I and II) which on further purification, were found to behave differently during hydrophobic chromatography and PAGE.These results indicated the presence of two isozymic forms of phenylalanine aminotransferase in bushbean shoots and both were found to catalyse transamination of the monochloro-phenylalanines examined in this study.
Taylor, David C.,Wightman, Frank
p. 1279 - 1288
(2007/10/02)