Molecular engineering and immobilization of lysine decarboxylase for synthesis of 1, 5-diaminopentane: a review / 生物工程学报

1, 5-diaminopentane, also known as cadaverine, is an important raw material for the production of biopolyamide. It can be polymerized with dicarboxylic acid to produce biopolyamide PA5X whose performances are comparable to that of the petroleum-based polyamide materials. Notably, biopolyamide uses renewable resources such as starch, cellulose and vegetable oil as substrate. The production process does not cause pollution to the environment, which is in line with the green and sustainable development strategy. The biosynthesis of 1, 5-diaminopentane mainly includes two methods: the de novo microbial synthesis and the whole cell catalysis. Lysine decarboxylase as the key enzyme for 1, 5-diaminopentane production, mainly includes an inducible lysine decarboxylase CadA and a constituent lysine decarboxylase LdcC. Lysine decarboxylase is a folded type Ⅰ pyridoxal-5' phosphate (PLP) dependent enzyme, which displays low activity and unstable structure, and is susceptible to deactivation by environmental factors in practical applications. Therefore, improving the catalytic activity and stability of lysine decarboxylase has become a research focus in this field, and molecular engineering and immobilization are the mainly approaches. Here, the mechanism, molecular engineering and immobilization strategies of lysine decarboxylase were reviewed, and the further strategies for improving its activity and stability were also prospected, with the aim to achieve efficient production of 1, 5-diaminopentane.

Cinnamic acid, ethanol and temperature interaction on coumarate decarboxylase activity and the relative expression of the putative cd gene in D. bruxellensis

Dekkera bruxellensis is one of the main contaminating yeasts in wine due to its ability to metabolize cinnamic acids into volatile phenols. This yeast metabolizes p-coumaric acid into 4-vinylphenol through a coumarate decarboxylase (CD) and then transforms it into to 4-ethylphenol (EF) through a vinylphenol reductase. In this work we investigated the influence of the interaction between the concentration of p-coumaric acid, ferulic acid and ethanol as well as growth temperature on the production of CD activity and the expression of a putative gene that codes for this enzymatic activity. For this, a Box Behnken experimental design was used. The concentration of p-coumaric acid (5-26 ppm) and ferulic acid (3-9 ppm) alone did not show any significant effect on any of the studied response variables. However, the interaction between (ethanol concentration * cinnamic acid concentration) and (ethanol concentration * temperature) had a significant statistical effect on the production of CD activity. Additionally, a higher growth temperature negatively affected the expression of the putative cd gene and the production of CD activity. This is the first work that studies the effect of cinnamic acids on the production of CD activity and the relative expression of its putative gene, using natural concentrations of cinnamic acid found in wine.

Changes in free polyamines and related enzymes during stipule and pod wall development in Pisum sativum.

Level of free polyamines, their key metabolic enzymes, and other features related to ageing were examined during stipule and pod wall development in pea (Pisum sativum). Free polyamine titre (per unit fresh mass) in both the organs, the specific activities of arginine decarboxylase and ornithine decarboxylase in the pod wall, gradually decreased with maturation. In stipule, these enzymes attained peak activity at 15 days after pod emergence and declined thereafter. Ornithine decarboxylase activity was greater in pod wall than in stipule; while, arginine decarboxylase activity was higher in stipule. Activity of degradative enzyme diamine oxidase increased with the onset of senescence in both the organs. Chlorophyll and electrical conductance had a inverse relationship throughout the experimental period, whereas, the chlorophyll content was directly related with polyamine levels in both stipule and pod wall during aging. On the other hand, protein and RNA contents were positively correlated with free polyamines throughout the test period in stipule, but in the pod wall this was true only for the later stages of development.

Importancia del metabolismo de la biotina / Importance of biotin metabolism

La biotina pertenece al grupo de las vitaminas hidrosolubles del complejo B. En humanos la biotina está directamente involucrada en importantes procesos metabólicos como la gluconeogénesis, la síntesis de ácidos grasos y el catabolismo de algunos aminoácidos, debido a su papel como grupo prostético de las enzimas piruvato carboxilasa, propionil-CoA carboxilasa, b-metilcrotonil-CoA carboxilasa y de la acetil-CoA carboxilasa. La biotina se une al sitio activo de estas enzimas y funciona como acarreador de CO2. Las carboxilasas se sintetizan como apocarboxilasas, carentes de biotina y la forma activa se produce por la unión covalente de la biotina al grupo e-amino de un residuo de lisina de la apocarboxilasa, reacción catalizada por la holocarboxilasa sintetasa. El paso final de la degradación de las carboxilasas es el rompimiento de la fracción biotinil del grupo e-amino de la lisina que es catalizada por la biotinidasa y resulta en la liberación de la biotina libre, la cual puede ser nuevamente reciclada. La biotina regula, a nivel postranscripcional, la expresión de la propionil-CoA carboxilasa y, a nivel transcripcional, a la de la holocarboxilasa sintetasa. Además de su papel como cofactor y regulador de la biosíntesis de las carboxilasas, la biotina está involucrada en otras áreas del metabolismo, donde regula la síntesis de proteínas específicas entre las que se encuentran el receptor de la asialoglicoproteína, varias enzimas reguladoras del metabolismo de glucosa y proteínas que unen biotina en la yema de huevo, entre otras. La deficiencia de biotina se ha reportado en pacientes sometidos a una alimentación parenteral total, en personas que ingieren grandes cantidades de clara de huevo crudo, en niños con desnutrición energético proteínica severa y en personas con errores innatos del metabolismo. Entre estas últimas se encuentran las enfermedades autosómicas recesivas del metabolismo de biotina que resultan de la alteración de la actividad de la holocarboxilasa sintetasa o de la biotinidasa.

o-Phthalaldehyde as a probe in the active site of phosphoenolpyruvate carboxylase.

Modification of phosphoenolpyruvate carboxylase with o-phthalaldehyde (OPA) resulted in rapid and irreversible inactivation exhibiting biphasic reaction kinetics. The kinetic analysis and correlation of spectral changes with activity indicated that inactivation by OPA results from the modification of two lysine and two cysteine residues per subunit of the enzyme. PEP plus Mg2+ offered substantial protection against modification. Some of the effectors also gave appreciable protection against modification indicating that the residues may be located at or close to the active site. Thus, the results indicate formation of two isoindoles showing the proximity of the essential lysine and cysteine residues at the active site.

Evaluacion de la capacidad de la desferrioxamina para revertir una severa porfiria inducida por hexaclorobenceno / Evaluation of desferrioxamine capacity to revert a severe porphyrid induced by hexachlorobenzene

El objeto del presente trabajo es investigar la capacidad de la desferrioxamina (DF) como quelante de hierro para disminuir o revertir una porfiria experimental severa inducida por hexaclorobenceno (HCB) en ratas. La DF se comienza a administrar después de 17 semanas de intoxicación con HCB y se continúa hasta la semana 27. Se cuantifican semanalmente excreciones en orina de ácido aminolevúlico (ALA), profobilinógeno y porfirinas. Al final del experimento se sacrifican los animales y se determinan porfirinas hepáticas y actividad de ALA sintetasa y porfirinógeno carboxi-liasa. Los resultados indican que el quelante adminsitrado no mejora el disturbio provocado por el HCB sobre el camino metabólico del hemo en las presentes condiciones. Se comparan estos resultados con los obtenidos cuando la DF se da conjuntamente con el HCB desde el comienzo de la administración del fungicida, situación en que sí el quelante retarda y atenúa el efecto porfirinogénico del HCB. Se discute el papel del hierro en la metabolización del HCB