Advances on microbial synthesis of L-proline and trans-4-hydroxy-L-proline / 生物工程学报

L-proline (L-Pro) is the only imino acid among the 20 amino acids that constitute biological proteins, and its main hydroxylated product is trans-4-hydroxy-L-proline (T-4-Hyp). Both of them have unique biological activities and play important roles in biomedicine, food and beauty industry. With the in-depth exploration of the functions of L-Pro and T-4-Hyp, the demand for them is gradually increasing. Traditional methods of biological extraction and chemical synthesis are unable to meet the demand of "green, environmental protection and high efficiency". In recent years, synthetic biology has developed rapidly. Through the intensive analysis of the synthetic pathways of L-Pro and T-4-Hyp, microbial cell factories were constructed for large-scale production, which opened a new chapter for the green and efficient production of L-Pro and T-4-Hyp. This paper reviews the application and production methods of L-Pro and T-4-Hyp, the metabolic pathways for microbial synthesis of L-Pro and T-4-Hyp, and the engineering strategies and advances on microbial production of L-Pro and T-4-Hyp, aiming to provide a theoretical basis for the "green bio-manufacturing" of L-Pro and T-4-Hyp and promote their industrial production.

Construction and application of a synthetic promoter library for Corynebacterium glutamicum / 生物工程学报

Promoter is an important genetic tool for fine-tuning of gene expression and has been widely used for metabolic engineering. Corynebacterium glutamicum is an important chassis for industrial biotechnology. However, promoter libraries that are applicable to C. glutamicum have been rarely reported, except for a few developed based on synthetic sequences containing random mutations. In this study, we constructed a promoter library based on the native promoter of odhA gene by mutating the -10 region and the bystanders. Using a red fluorescent protein (RFP) as the reporter, 57 promoter mutants were screened by fluorescence imaging technology in a high-throughput manner. These mutants spanned a strength range between 2.4-fold and 19.6-fold improvements of the wild-type promoter. The strongest mutant exhibited a 2.3-fold higher strength than the widely used strong inducible promoter Ptrc. Sequencing of all 57 mutants revealed that 55 mutants share a 1-4 bases shift (4 bases shift for 68% mutants) of the conserved -10 motif "TANNNT" to the 3' end of the promoter, compared to the wild-type promoter. Conserved T or G bases at different positions were observed for strong, moderate, and weak promoter mutants. Finally, five promoter mutants with different strength were employed to fine-tune the expression of γ-glutamyl kinase (ProB) for L-proline biosynthesis. Increased promoter strength led to enhanced L-proline production and the highest L-proline titer of 6.4 g/L was obtained when a promoter mutant with a 9.8-fold higher strength compared to the wild-type promoter was used for ProB expression. The use of stronger promoter variants did not further improve L-proline production. In conclusion, a promoter library was constructed based on a native C. glutamicum promoter PodhA. The new promoter library should be useful for systems metabolic engineering of C. glutamicum. The strategy of mutating native promoter may also guide the construction of promoter libraries for other microorganisms.

Addition of synthetic amino acids in sheep semen improves its quality after cryopreservation / Adição de aminoácidos sintéticos no sêmen ovino melhora a qualidade espermática após a criopreservação do sêmen

Some amino acids can protect mammalian sperm cells against oxidation during thermal stress caused by freezing/thawing. Thus, the objective was to evaluate the protective action of the association of the amino acids L-proline (Pro) and L-glutamine (Glu) against the cryoinjury caused to sheep sperm after cryopreservation. Eight ejaculates were collected from four sheep (n=32) and diluted in Tris-Egg Yolk-Glycerol until the final concentration of 200 x106 sptz/mL and kept in a water bath at 32 °C. The amino acids were added as follows: control (without adding amino acids), Pro+Glu 1 (100 M Pro + 500 M Glu), Pro+Glu 2 (300 M Pro + 1000 M Glu), Pro+Glu 3 (500 M Pro + 1500 M Glu) and Pro+Glu 4 (700 M Pro + 2000 M Glu). Afterwards, the semen was cooled to 5 °C for 2 h, after that period, filled in 0.5 mL straws and then placed under liquid nitrogen vapor (N2L), 8 cm from the liquid sheet for 15 min, and then immersed on the N2L. The samples were analyzed for sperm motility, plasma membrane and acrosomal membrane integrity, mitochondrial activity and binding test. The variables were subjected to the normality tests (Lilliefors test) and homoscedasticity tests (Cochran and Bartlett test), afterwards the variables of normal distribution were subjected to analysis of variance and the means compared by the Tukey test with a significance level of 5%. The Pro+Glu 3 group exhibited sp

Alguns aminoácidos podem proteger as células espermáticas de mamíferos contra a oxidação durante o estresse térmico causado na congelação/descongelação. Dessa forma, objetivou-se avaliar a ação protetora da associação dos aminoácidos L-prolina (Pro) e L-glutamina (Glu) contra as crioinjúrias causadas aos espermatozoides de ovino após a criopreservação. Foram coletados oito ejaculados de quatro carneiros (n=32) e diluídos em Tris-Gema de ovo-Glicerol até a concentração final de 200 x106 sptz/mL e, mantidos em banho maria a 32 °C. Os aminoácidos foram adicionados da seguinte forma: controle (sem adição de aminoácidos), Pro+Glu 1 (100 μM Pro + 500 μM Glu), Pro+Glu 2 (300 μM Pro + 1000 μM Glu), Pro+Glu 3 (500 μM Pro + 1500 μM Glu) e Pro+Glu 4 (700 μM Pro + 2000 μM Glu). Depois, o sêmen foi resfriado a 5 °C por 2 h, após esse período, envasado em palhetas de 0,5 mL e então acondicionado sob vapor de nitrogênio líquido (N2L), a 8 cm da lâmina líquida por 15 min, e depois imersos no N2L. As amostras foram analisadas quanto à motilidade espermática, integridade da membrana plasmática e da membrana acrossomal, atividade mitocondrial e teste de ligação. As variáveis foram submetidas aos testes de normalidade (Teste de Lilliefors) e homocedacidade (Teste de Cochran e Bartlett), posteriormente as variáveis de distribuição normal foram submetidas à análise de variância e as médias comparadas pelo teste de Tukey com nível de significância de 5%. O grupo Pro+Glu 3 exibiu espermatozoides com uma maior (P<0,05) motilidade após o descongelamento. Além disso o maior percentual de integridade da membrana plasmatica e acrossomal foram obtidos utilizando Pro+Glu 1, Pro+Glu 2 e Pro+Glu 3; e Pro+Glu 2 e Pro+Glu 3, respectivamente. Os aminoácidos também mantiveram alta a atividade mitocondrial em comparação com o controle, com Pro+Glu 3 resultando numa maior atividade (P<0,05). A viabilidade dos espermatozoides foi maior (P<0,05) com o uso de Pro+Glu 2 e Pro+Glu 3 do que no controle. O número de espermatozoides que apresentaram à capacidade de ligação a membrana perivitelina da gema de ovo foi maior (P<0,05) no sêmen tratado com aminoácidos.

Addition of synthetic amino acids in sheep semen improves its quality after cryopreservation / Adição de aminoácidos sintéticos no sêmen ovino melhora a qualidade espermática após a criopreservação do sêmen

Some amino acids can protect mammalian sperm cells against oxidation during thermal stress caused by freezing/thawing. Thus, the objective was to evaluate the protective action of the association of the amino acids L-proline (Pro) and L-glutamine (Glu) against the cryoinjury caused to sheep sperm after cryopreservation. Eight ejaculates were collected from four sheep (n=32) and diluted in Tris-Egg Yolk-Glycerol until the final concentration of 200 x106 sptz/mL and kept in a water bath at 32 °C. The amino acids were added as follows: control (without adding amino acids), Pro+Glu 1 (100 µM Pro + 500 µM Glu), Pro+Glu 2 (300 µMPro + 1000 µM Glu), Pro+Glu 3 (500 µM Pro + 1500 µM Glu) and Pro+Glu 4 (700 µM Pro + 2000 µM Glu). Afterwards, the semen was cooled to 5 °C for 2 h, after that period, filled in 0.5 mL straws and then placed under liquid nitrogen vapor (N2L), 8 cm from the liquid sheet for 15min, and then immersed on the N2L. The samples were analyzed for sperm motility, plasma membrane and acrosomal membrane integrity, mitochondrial activity and binding test. The variables were subjected to the normality tests (Lilliefors test) and homoscedasticity tests (Cochran and Bartlett test), afterwards the variables of normal distribution were subjected to analysis of variance and the means compared by the Tukey test with a significance level of 5%. The Pro+Glu 3 group exhibited sperm with a greater (P<0.05) motility after thawing. In addition, the highest percentage of plasma and acrosomal membrane integrity were obtained using Pro+Glu 1, Pro+Glu 2 and Pro+Glu 3; and Pro+Glu 2 and Pro+Glu 3, respectively. Amino acids also kept mitochondrial activity high compared to the control, with Pro+Glu 3 resulting in greater activity (P<0.05). Sperm viability was higher (P<0.05) with the use of Pro+Glu 2 and Pro+Glu 3 than in the control. The number of sperm that showed the ability to bind to the egg yolk perivitelline membrane was higher (P<0.05) in semen treated with amino acids. It is concluded that the addition of synthetic amino acids in the semen of sheep before cryopreservation improves sperm quality and fertilization potential and can thus be added in cryopreservation protocols.

Alguns aminoácidos podem proteger as células espermáticas de mamíferos contra a oxidação durante o estresse térmico causado na congelação/descongelação. Dessa forma, objetivou-se avaliar a ação protetora da associação dos aminoácidos L-prolina (Pro) e L-glutamina (Glu) contra as crioinjúrias causadas aos espermatozoides de ovino após a criopreservação. Foram coletados oito ejaculados de quatro carneiros (n=32) e diluídos em Tris-Gema de ovo-Glicerol até a concentração final de 200 x106 sptz/mL e, mantidos em banho maria a 32 °C. Os aminoácidos foram adicionados da seguinte forma: controle (sem adição de aminoácidos), Pro+Glu 1 (100 µM Pro + 500 µM Glu), Pro+Glu 2 (300 µM Pro + 1000 µM Glu), Pro+Glu 3 (500 µM Pro + 1500 µM Glu) e Pro+Glu 4 (700 µM Pro + 2000 µM Glu). Depois, o sêmen foi resfriado a 5 °C por 2 h, após esse período, envasado em palhetas de 0,5 mL e então acondicionado sob vapor de nitrogênio líquido (N2L), a 8 cm da lâmina líquida por 15 min, e depois imersos no N2L. As amostras foram analisadas quanto à motilidade espermática, integridade da membrana plasmática e da membrana acrossomal, atividade mitocondrial e teste de ligação. As variáveis foram submetidas aos testes de normalidade (Teste de Lilliefors) e homocedacidade (Teste de Cochran e Bartlett), posteriormente as variáveis de distribuição normal foram submetidas à análise de variância e as médias comparadas pelo teste de Tukey com nível de significância de 5%. O grupo Pro+Glu 3 exibiu espermatozoides com uma maior (P<0,05) motilidade após o descongelamento. Além disso o maior percentual de integridade da membrana plasmatica e acrossomal foram obtidos utilizando Pro+Glu 1, Pro+Glu 2 e Pro+Glu 3; e Pro+Glu 2 e Pro+Glu 3, respectivamente. Os aminoácidos também mantiveram alta a atividade mitocondrial em comparação com o controle, com Pro+Glu 3 resultando numa maior atividade (P<0,05). A viabilidade dos espermatozoides foi maior (P<0,05) com o uso de Pro+Glu 2 e Pro+Glu 3 do que no controle. O número de espermatozoides que apresentaram à capacidade de ligação a membrana perivitelina da gema de ovo foi maior (P<0,05) no sêmen tratado com aminoácidos. Conclui-se que, a adição dos aminoácidos sintéticos no sêmen de ovinos antes da criopreservação melhora a qualidade espermática e o potencial fecundante, podendo assim serem adicionados em protocolos de criopreservação.

Risk Assessment of "Other Substances" – L-proline

The Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) has, at the request of the Norwegian Food Safety Authority (Mattilsynet; NFSA), assessed the risk of "other substances" in food supplements and energy drinks sold in Norway. VKM has assessed the risk of doses given by NFSA. These risk assessments will provide NFSA with the scientific basis while regulating "other substances" in food supplements. "Other substances" are described in the food supplement directive 2002/46/EC as substances other than vitamins or minerals that have a nutritional and/ or physiological effect. It is added mainly to food supplements, but also to energy drinks and other foods. In this series of risk assessments of "other substances" VKM has not evaluated any claimed beneficial effects from these substances, only possible adverse effects. The present report is a risk assessment of specified doses of L-proline in food supplements, and it is based on previous risk assessments and articles retrieved from literature searches. According to information from NFSA, L-proline is an ingredient in food supplements sold in Norway. NSFA has requested a risk assessment of 50, 500, 1000, 1500 and 1800 mg/day of L-proline from food supplements. L-proline is considered a non-essential amino acid as it can be synthesised from arginine via the urea cycle in liver, and from glutamine/glutamic acid in the intestinal epithelium. In addition, L-proline is ingested through the diet. All protein rich foods provide L-proline, and animal proteins from milk and meat are particularly abundant sources. A dietary requirement for proline in healthy humans has not been estimated since proline is not considered an essential amino acid. Data on dietary intake of L-proline in Norway are not available. In the third US National Health and Nutrition Examination Survey (NHANES III; 1988-1994), overall mean intake of L-proline from food and supplements was 5.2 g/day. A previous report from the Institute of Medicine (2005) cited one small uncontrolled patient study (n=4) and two animal studies, none of which assessed the toxicity of L-proline in a dose-response manner. The report concluded that a tolerable upper intake level for L-proline could not be determined. In a risk grouping of amino acids from VKM (2011), proline was categorised as having potentially moderate risk, based on the scarce literature and the notion that amino acids are generally bioactive compounds. It was stated that "no conclusion can be drawn on a scientific basis due to lack of adequate scientific literature. Nor will it be possible to conduct a risk assessment until further studies are available". Three systematic literature searches without restriction on publication year were performed for the current risk assessment, aimed at identifying adverse effects of L-proline supplementation in human and animal studies. In humans, one uncontrolled experimental study was identified where a single oral dose of 500 mg/kg bw L-proline was administered as a growth hormone stimulatory agent to 20 children with hyposomatotropic dwarfism and 20 healthy children. No adverse effects were observed. In animals, one relevant subchronic (90 days) toxicological dose-response study in rats was included and forms the basis for the current risk assessment. In that study, performed in accordance with official guidelines from the Japanese Ministry of Health, Labour and Welfare, there were no indications of toxicity at the highest dose given through a powder diet (5.0% L-proline). This dose corresponded to 2773 mg L-proline/kg bw per day and was used as a no-observed-adverse-effect-level (NOAEL). Studies to set a tolerance level for L-proline for children or adolescents have not been found. Therefore, an assumption is made that these age groups have similar tolerance as adults relative to their body weight. To evaluate the safety of the specific doses given by NFSA, margin of exposure (MOE) was calculated with use of 2773 mg L-proline/kg bw per day as NOAEL. For the highest dose (1800 mg/day) MOE is 67 (= 2773* 43.3/1800) in children 10 to <14 years (default body weight 43.3 kg), and 94 (= 2773* 61.3/1800) in adolescents 14 to <18 years (default body weight 61.3 kg). For the dose of 1500 mg/day, the MOE in children is 80. MOE for all the other doses and age categories are above 100. Based on the magnitude of MOE, the lack of adverse effects at the highest dose tested (current NOAEL) and the notion that L-proline is a nutrient that is synthesised endogenously from other amino acids in addition to a dietary intake in the magnitude of 5 grams per day, VKM concludes that: In adults (≥18 years), the specified doses 50, 500, 1000, 1500 and 1800 mg/day Lproline in food supplements are unlikely to cause adverse health effects. In adolescents (14 to <18 years), the specified doses 50, 500, 1000, 1500 and 1800 mg/day L-proline in food supplements are unlikely to cause adverse health effects. In children (10 to <14 years), the specified doses 50, 500, 1000, 1500 and 1800 mg/day L-proline in food supplements are unlikely to cause adverse health effects. Children younger than 10 years were not within the scope of the present risk assessment.

Study on secondary metabolites of endophytic fungus Fusarium lactis from Dendrobium huoshanense / 中草药

Objective To study the secondary metabolites of endophytic fungus Fusarium lactis in Dendrobium huoshanense. Methods Compounds were isolated from the EtOAc extract by chromatography technology and their structures were elucidated on the basis of comprehensive spectroscopic analysis. Results Twenty-one compounds were isolated and identified as N-phenethylacetamide (1), 1H-indole-3-carbaldehyde (2), thymidine (3), uracil (4), lignoren (5), uridine (6), hexahydrate (7), adenosine (8), cyclo-glycine-(L)-proline (9), cyclo (D)-proline-(L)-phenylalanine (10), cyclo (L)-proline-(L)-phenylalanine (11), 2-pyrrolidinone (12), N-methyl-2-pyrolidinone (13), cyclo-(L)-4-OH-proline-(L)-phenylalanine (14), brevianamide F (15), 3-methyl- piperazine-2,5-dione (16), 7,8-dimethylbenzo[g]pteridine-2,4 (1H,3H)-dione (17), cyclo (L)-tyrosine-(L)-phenylalanine (18), beer sterols (19), daidzein (20), and erythritol (21). Conclusion All compounds are isolated from Fusarium lactis for the first time.

Atividade anti-inflamatória e antinociceptiva da N-Metil-Trans-4-Hidroxi-L-Prolina isolado das folhas de Sideroxylon obtusifolium

Sideroxylum obtusifolium (Humb. ex. Roem. & Schult) T.B. Penn (Sapotaceae) de ocorrência comum na América do Sul, é conhecida no Nordeste do Brasil como “quixabeira”. Os decoctos da cascado caulee das folhas são utilizados na medicina popular como anti-inflamatório. O presente estudo avaliou in vitroe in vivoas propriedades anti-inflamatórias e antinociceptivas do composto N-metil-trans-4-hidroxi-L-prolina (NMP) isolado das folhas de Sideroxylon obtusifolium. Camundongos Swissmachos (25-30g; n=8-10) foram utilizados nos testes da formalina, contorções abdominais induzidas por ácido acético, capsaicina e Von-Frey. Os efeitos anti-inflamatórios foram investigados através dos testes do edema depata e de peritonite, ambos induzidos por carragenina. Foram investigados possíveis mecanismos de ação da NMP através de bloqueio farmacológico por naloxona, ioimbina e glibenclamida. As patas inflamadas pela carragenina foram coletadaseem seguida encaminhadas para o estudo histológico e ensaio imunohistoquímico para TNF-α, iNOS, COX-2 e NF-kB. Foi verificada a participação de neutrófilos através da dosagem de mieloperoxidade (MPO) e a atividade antioxidante foi testada pelo método de DPPH.Os resultados mostraram redução de 35, 42 e 52% na 1º fase (neurogênica) e de 30, 61 e 78% na 2º fase (inflamatória) do teste de formalina, eem 34, 53 e 72% nas contorções abdominais/20 min, induzidas por ácido acético,nas doses de 25, 50 e 100 mg/kg, respectivamente (P<0,05). A NMP (100 mg/kg) diminuiu a hipernocicepção no teste da capsaicina e de Von-Frey (P<0,05). Houve redução do edema após os tratamentos com a NMP em todos os períodos (P<0,05)...

Sideroxylum obtusifolium(Humb. Ex. Roem. & Schult) T. B. Penn (Sapotaceae) of common occurrence in South America, is known in the Northeast of Brazil as "Quixabeira". The decoctions from the stem bark and leaves are used in folk medicine as anti-inflammatory. The present study evaluated by in vitro and in vivo models the anti-inflammatory and antinociceptive effects of the compound N-methyl-trans-4-hydroxy-L-proline (NMP) isolated from the leaves of Sideroxylon obtusifolium. Male Swiss mice (25-30 g; n = 8-10) were used in the tests of formalin, abdominal contractions induced by aceticacid, capsaicin and von-Frey. Anti-inflammatory effects were investigated using the tests of paw edema and peritonitis, both induced by carrageenan. We investigated possible mechanisms of action of NMP through the pharmacological blockade by naloxone, yohimbine and glibenclamide. Furthermore, the inflamed legs by carrageenan were collected and then sent for histological and immunohistochemical assay for TNF-α, iNOS, COX-2 and NF-kB. The participation of neutrophils was verified by myeloperoxidase dosage (MPO) and the antioxidant activity was tested by the DPPH method. The results showed reductions of 35, 42 and 52% in the 1st phase (neurogenic) and of 30, 61 and 78% in the 2nd phase (inflammatory) of the formalin test, and of 34, 53 and 72% in the writhings /20 min induced by acetic acid at the doses of 25, 50 and 100 mg / kg, respectively (P <0.05). NMP (100 mg / kg) reduced the hyperalgesia in the capsaicin and Von-Frey tests (P <0.05). There was a reduction of edema after treatment with NMP at all periods (P <0.05)...

Validación de un método por CLAR para la cuantificación de L-prolina en la tintura al 20 por ciento de Murraya paniculata L. Jack / Validation of a high performance liquid chromatography method for quantitation of L-proline in 20 percent tincture from Murraya paniculata L. Jack

INTRODUCCIÓN: la búsqueda de técnicas analíticas para el control de la calidad de los medicamentos constituye un aspecto de gran interés en el campo farmacéutico, más si van dirigidas al estudio del o los marcadores químicos de las plantas medicinales, sus extractos y fitomedicamentos. OBJETIVO: validar un método de cromatografía líquida de alta resolución (CLAR) para la determinación cuantitativa del aminoácido L-prolina como sustancia marcador en la tintura de Murraya paniculata L. Jack. MÉTODOS: en el método por CLAR, la separación se realizó en una columna C-18 (UP5ODB-150/046), se utilizó como fase móvil una mezcla de solución buffer fosfato, pH ajustado a 2,4 y acetonitrilo (70:30 v/v), con una velocidad de flujo de 0,6 mL/min, modo isocrático, con detección ultravioleta a 440 nm. El volumen de inyección de la muestra fue de 20 µL. El método fue validado según la categoría I, siguiendo las exigencias internacionales. RESULTADOS: la curva de calibración fue lineal en el rango de concentraciones ensayadas (30 a 375 µg/mL), se observó una buena precisión con coeficientes de variación menores del 2 por ciento. Los valores de recobrado estuvieron dentro de los límites establecidos para los métodos cromatográficos (98-102 por ciento). Se demostró la especificidad del método, al no presentarse interferencias de picos adicionales en la zona de elusión del compuesto de interés (L-prolina). CONCLUSIONES: el método analítico por CLAR, validado para la cuantificación del aminoácido L-prolina en la tintura de M. paniculata, demostró ser lineal, preciso, exacto y específico bajo las condiciones de estudio(AU)

INTRODUCTION: the search for analytical methods that may monitor the quality of drugs is an issue of great interest in the pharmaceutical field, even more if they are directed to studying chemical markers of medicinal plants, their extracts and phytomedicines. OBJECTIVE: to validate a high-resolution liquid chromatography (HPLC) method for the quantitative determination of the L-proline amino acid as a marker substance in Murraya paniculata L. Jack tincture. METHODS: in the HPLC, the separation was performed on a C-18 (UP5ODB-150/046) column, with a mixture of phosphate buffer solution, pH adjusted to 2.4 and acetonitrile (70:30 v/v) used as mobile phase, the flow rate was 0.6 mL/min, isocratic mode with UV detection set at 440 nm. The injection volume of the sample was 20 µL. The method was validated according to category I, following international requirements. RESULTS: the calibration curve was linear over the concentration range tested (30-375 mg/mL), good precision was observed with a variation coefficient less than 2 percent. Recovery values were within the limits for chromatographic methods (98-102 percent). The method was specific since there was no-interference by additional peaks in the elution zone of the compound in question (L-proline). CONCLUSIONS: the HPLC analytical method, validated for the quantification of L-proline amino acid in M. paniculata tincture, proved to be linear, precise, accurate and specific under the study conditions(AU)