Production of L-DOPA under heterogeneous asymmetric catalysis

A validated LC-MS/MS method for quantitative determination of L-dopa in Fagioli di Sarconi beans (Phaseolus vulgaris L.)

An analytical method based on ultrasound assisted extraction (UAE) and liquid chromatography coupled to electrospray tandem mass spectrometry (LC-ESI/MS/MS) was validated and applied for determining L-dopa in four ecotypes of Fagioli di Sarconi beans (Phaseolus vulgaris L.), marked with the European label PGI (Protected Geographical Indication). The selectivity of the proposed method was ensured by the specific fragmentation of the analyte. Simple isocratic chromatographic conditions and mass spectrometric detection in multiple reaction monitoring (MRM) acquisition mode were used for sensitive quantification. The LC-ESI/MS/MS method was validated within a linear range of 0.001-5.000 μg/mL. Values of 0.4 and 1.1 ng/mL were obtained for the limits of detection and quantification, respectively. The repeatability, inter-day precision, and recovery values ranges were 0.6%-4.5%, 5.4%-9.9%, and 83%-93%, respectively. Fresh and dried beans, as well as pods, cultivated exclusively with organic methods avoiding any synthetic fertilizers and pesticides were analyzed showing an L-dopa content ranging from 0.020 ± 0.005 to 2.34 ± 0.05 μg/g dry weight.

An Overview of Methods for L-Dopa Extraction and Analytical Determination in Plant Matrices

L-dopa is a precursor of dopamine used as the most effective symptomatic drug treatment for Parkinson's disease. Most of the L-dopa isolated is either synthesized chemically or from natural sources, but only some plants belonging to the Fabaceae family contain significant amounts of L-dopa. Due to its low stability, the unambiguous determination of L-dopa in plant matrices requires appropriate technologies. Several analytical methods have been developed for the determination of L-dopa in different plants. The most used for quantification of L-dopa are mainly based on capillary electrophoresis or chromatographic methods, i.e., high-performance liquid chromatography (HPLC), coupled to ultraviolet-visible or mass spectrometric detection. HPLC is most often used. This paper aims to give information on the latest developments in the chemical study of L-dopa, emphasizing the extraction, separation and characterization of this compound by chromatographic, electrochemical and spectral techniques. This study can help select the best possible strategy for determining L-dopa in plant matrices using advanced analytical methods.

Rapid production of l-DOPA by Vibrio natriegens, an emerging next-generation whole-cell catalysis chassis

3, 4‐Dihydroxyphenyl‐l‐alanine (l‐DOPA) is a compound of high medical value and is considered effective as a treatment for Parkinson’s disease. Currently, bioproduction of l‐DOPA is mainly carried out by whole‐cell catalysis mediated by recombinant Escherichia coli carrying heterogeneous tyrosine phenol lyase. Vibrio natriegens is increasingly attracting attention owing to its superiority, including extremely rapid growth and high soluble protein expression capacity. In this study, we attempt to develop an efficient whole‐cell catalyst for l‐DOPA production using V. natriegens as the chassis. The maximum soluble protein expression by V. natriegens was accomplished in 4 h at 37°C, which was equivalent to that achieved by E. coli in 16 h at 16°C. Furthermore, the maximum productivity reached over 10.0 g l⁻¹ h⁻¹ in the early stage of biocatalysis, nearly two‐fold higher than previously reported. Approximately 54.0 g l⁻¹l‐DOPA was obtained with a catechol conversion rate greater than 95%. In conclusion, V. natriegens displays advantages, including rapid protein expression and catalytic rate in the catalysis process for l‐DOPA production. These findings strongly suggest that V. natriegens has remarkable potential as a whole‐cell catalysis chassis for the production of valuable chemicals.

L-Dopa in small peptides: an amazing functionality to form supramolecular materials

l-Dopa (3,4-dihydroxyphenylalanine) is a chiral amino acid generated via biosynthesis from l-tyrosine in plants and some animals. The presence of multiple interacting sites makes l-Dopa a multifunctional building block for the preparation of supramolecular materials. The possibility to form hydrogen bonds and the presence of the aromatic ring allow l-Dopa molecules to interact through a series of non-covalent interactions. The additional presence of the catechol moiety really makes this compound unique: not only does it have implications in the self-assembly process of Dopa itself and with other substrates, but also it highly increases the number of applications of the final material, since it works as an antioxidant, radical trapper, metal chelator, reducing agent and adhesive. l-Dopa and catechol containing derivatives have been extensively introduced inside both synthetic and natural polymers to obtain amazing functional materials. In this review we report the preparation of small peptides containing l-Dopa, focusing on the supramolecular materials that can be obtained with them, ranging from fibrils to fibres, gels, films and coatings, all having the different applications mentioned above and many others.

Efficient strategies to enhance plasmid stability for fermentation of recombinant Escherichia coli harboring tyrosine phenol lyase

OBJECTIVE

To solve the bottleneck of plasmid instability during microbial fermentation of L-DOPA with recombinant Escherichia coli expressing heterologous tyrosine phenol lyase.

RESULTS

The tyrosine phenol lyase from Fusobacterium nucleatum was constitutively expressed in E. coli and a fed-batch fermentation process with temperature down-shift cultivation was performed. Efficient strategies including replacing the original ampicillin resistance gene, as well as inserting cer site that is active for resolving plasmid multimers were applied. As a result, the plasmid stability was increased. The co-use of cer site on plasmid and kanamycin in culture medium resulted in proportion of plasmid containing cells maintained at 100% after fermentation for 35 h. The specific activity of tyrosine phenol lyase reached 1493 U/g dcw, while the volumetric activity increased from 2943 to 14,408 U/L for L-DOPA biosynthesis.

CONCLUSIONS

The established strategies for plasmid stability is not only promoted the applicability of the recombinant cells for L-DOPA production, but also provides important guidance for industrial fermentation with improved microbial productivity.

Site-directed mutagenesis to improve the thermostability of tyrosine phenol-lyase

3,4-Dihydroxyphenyl-L-alanine (L-DOPA) is the most important antiparkinsonian drug, and tyrosine phenol-lyase (TPL)-based enzyme catalysis process is one of the most adopted methods on industrial scale production. TPL activity and stability represent the rate-limiting step in L-DOPA synthesis. Here, 25 TPL mutants were predicted, and two were confirmed as exhibiting the highest L-DOPA production and named E313W and E313M. The L-DOPA production from E313W and E313M was 47.5 g/L and 62.1 g/L, which was 110.2 % and 174.8 % higher, respectively, than that observed from wild-type (WT) TPL. The K_m of E313W and E313M showed no apparent decrease, whereas the k_cat of E313W and E313M improved by 45.5 % and 36.4 %, respectively, relative to WT TPL. Additionally, E313W and E313M displayed improved thermostability, a higher melting temperature, and enhanced affinity between for pyridoxal-5'-phosphate. Structural analysis of the mutants suggested increased stability of the N-terminal region via enhanced interactions between the mutated residues and H317. Application of these mutants in a substrate fed-batch strategy as whole-cell biocatalysts allows realization of a cost-efficient short fermentation period resulting in high L-DOPA yield.

Integrating enzyme evolution and high-throughput screening for efficient biosynthesis of l-DOPA

l-DOPA is a key pharmaceutical agent for treating Parkinson’s, and market demand has exploded due to the aging population. There are several challenges associated with the chemical synthesis of l-DOPA, including complicated operation, harsh conditions, and serious pollution. A biocatalysis route for l-DOPA production is promising, especially via a route catalyzed by tyrosine phenol lyase (TPL). In this study, using TPL derived from Erwinia herbicola (Eh-TPL), a mutant Eh-TPL was obtained by integrating enzyme evolution and high-throughput screening methods. l-DOPA production using recombinant Escherichia coli BL21 (DE3) cells harbouring mutant Eh-TPL was enhanced by 36.5% in shake flasks, and the temperature range and alkali resistance of the Eh-TPL mutant were promoted. Sequence analysis revealed two mutated amino acids in the mutant (S20C and N161S), which reduced the length of a hydrogen bond and generated new hydrogen bonds. Using a fed-batch mode for whole-cell catalysis in a 5 L bioreactor, the titre of l-DOPA reached 69.1 g L−1 with high productivity of 11.52 g L−1 h−1, demonstrating the great potential of Eh-TPL variants for industrial production of l-DOPA.

Metabolic engineering of Escherichia coli BL21 (DE3) for de novo production of L-DOPA from D-glucose

Background

Production of l-tyrosine is gaining grounds as the market size of 3,4-dihydroxyphenyl-l-alanine (l-DOPA) is expected to increase due to increasing cases of Parkinson’s disease a neurodegenerative disease. Attempts to overproduce l-tyrosine for conversion to l-DOPA has stemmed on the overexpressing of critical pathway enzymes, an introduction of feedback-resistant enzymes, and deregulation of transcriptional regulators.

Results

An E. coli BL21 (DE3) was engineered by deleting tyrR, ptsG, crr, pheA and pykF while directing carbon flow through the overexpressing of galP and glk. TktA and PpsA were also overexpressed to enhance the accumulation of E4P and PEP. Directed evolution was then applied on HpaB to optimize its activity. Three mutants, G883R, G883A, L1231M, were identified to have improved activity as compared to the wild-type hpaB showing a 3.03-, 2.9- and 2.56-fold increase in l-DOPA production respectively. The use of strain LP-8 resulted in the production of 691.24 mg/L and 25.53 g/L of l-DOPA in shake flask and 5 L bioreactor, respectively.

Conclusion

Deletion of key enzymes to channel flux towards the shikimate pathway coupled with the overexpression of pathway enzymes enhanced the availability of l-tyrosine for L-DOPA production. Enhancing the activity of HpaB increased l-DOPA production from glucose and glycerol. This work demonstrates that increasing the availability of l-tyrosine and enhancing enzyme activity ensures maximum l-DOPA productivity.

Electronic supplementary material

The online version of this article (10.1186/s12934-019-1122-0) contains supplementary material, which is available to authorized users.

Overview on the biotechnological production of L-DOPA

L-DOPA (3,4-dihydroxyphenyl-L-alanine) has been widely used as a drug for Parkinson's disease caused by deficiency of the neurotransmitter dopamine. Since Monsanto developed the commercial process for L-DOPA synthesis for the first time, most of currently supplied L-DOPA has been produced by the asymmetric method, especially asymmetric hydrogenation. However, the asymmetric synthesis shows critical limitations such as a poor conversion rate and a low enantioselectivity. Accordingly, alternative biotechnological approaches have been researched for overcoming the shortcomings: microbial fermentation using microorganisms with tyrosinase, tyrosine phenol-lyase, or p-hydroxyphenylacetate 3-hydroxylase activity and enzymatic conversion by immobilized tyrosinase. Actually, Ajinomoto Co. Ltd commercialized Erwinia herbicola fermentation to produce L-DOPA from catechol. In addition, the electroenzymatic conversion system was recently introduced as a newly emerging scheme. In this review, we aim to not only overview the biotechnological L-DOPA production methods, but also to briefly compare and analyze their advantages and drawbacks. Furthermore, we suggest the future potential of biotechnological L-DOPA production as an industrial process.

β-amino esters from the reductive ring opening of aziridine-2-carboxylates

A general study is undertaken to examine the scope of the reductive ring opening of aziridine-2-carboxylates with samarium diiodide. The competition between C-C and C-N bond cleavage is examined as a function of the nature of the N-substituent of the aziridine, the nature of the substituent in the 3-position of the aziridine, and whether the substituent in the 3-position is in a cis or trans relationship with the carboxylate in the 2-position. The desired C-N bond cleavage leads to β-amino esters that are the predominant products for most aziridines with an N-activating group. However, C-C cleavage products are observed with an aryl group in the 3-position; this can be particularly pronounced with cis-aziridines where a nearly equal mixture of the two is observed. Exclusive formation of the C-N cleavage product is observed for all aziridines with the strongly N-activating p-toluene sulfonate group. Similarly high selectivity is observed for the 2-trimethylsilylethyl sulfonate group (SES), which is easier to remove. The utility of these methods is illustrated in the synthesis of protected forms of (R)-β(3)-DOPA and L-DOPA from the same aziridine, the former by SmI2-mediated reductive opening at C-2 and the latter by palladium-mediated reductive opening at C-3.

Bioconversion of L-tyrosine to L-DOPA by a novel bacterium Bacillus sp. JPJ

L-DOPA is an amino acid derivative and most potent drug used against Parkinson's disease, generally obtained from Mucuna pruriens seeds. In present communication, we have studied the in vitro production of L-DOPA from L-tyrosine by novel bacterium Bacillus sp. JPJ. This bacterium produced 99.4% of L-DOPA from L-tyrosine in buffer (pH 8) containing 1 mg ml(-1) cell mass incubated at 40°C for 60 min. The combination of CuSO(4) and L-ascorbic acid showed the inducing effect at concentrations of 0.06 and 0.04 mg ml(-1), respectively. The activated charcoal 2 mg ml(-1) was essential for maximum bioconversion of L-tyrosine to L-DOPA and the crude tyrosinase activity was 2.7 U mg(-1) of tyrosinase. Kinetic studies showed significant values of Y (p/s) (0.994), Q (s) (0.500) and q (s) (0.994) after optimization of the process. The production of L-DOPA was confirmed by analytical techniques such as HPTLC, HPLC and GC-MS. This is the first report on rapid and efficient production of L-DOPA from L-tyrosine by bacterial source which is more effective than the plant, fungal and yeast systems.

Electroenzymatic synthesis of l-DOPA

Parkinson's disease is caused by a deficiency of the neurotransmitter dopamine. Since l-DOPA (l-3,4-dihydroxyphenylalanine) is a precursor of dopamine and can pass across the blood-brain barrier, it has been used as a treatment for Parkinson's disease. Hundreds tons of l-DOPA are produced per year, and most of the current supply is produced by a chemical method of asymmetric synthesis. However, the chemical process for l-DOPA synthesis requires an expensive metal catalyst and shows low conversion rates and low enantioselectivity. In this study, we developed a novel technology for the production of l-DOPA, an electroenzymatic synthesis with a tyrosinase-immobilized cathode under the reduction potential of DOPAquinone, which is -530 mV. Compared to other approaches for l-DOPA synthesis reported previously, this electroenzymatic system showed the highest conversion rate and a highly enhanced productivity of up to 95.9% and 47.27 mg l(-1)h(-1), respectively.

Pseudo-peptides derived from isomannide: inhibitors of serine proteases

In this paper, we describe the synthesis of a novel class of pseudo-peptides derived from isomannide and several oxazolones as potential inhibitors of serine proteases as well as preliminary pharmacological assays for hepatitis C. Hepatitis C, dengue and West Nile fever are among the most important flaviviruses that share one important serine protease enzyme. Serine proteases belong to the most studied class of proteolytic enzymes and are a primary target in the drug development field. Several pseudo-peptides were obtained in good yields from the reaction of isomannide and oxazolones, and their anti-HCV potential using the HCV replicon-based assay was shown.