Producción recombinante de la enteroquinasa de cadena ligera bovina en el periplasma de Escherichia coli.

La enteroquinasa es una peptidasa que se produce en la mucosa duodenal bovina, la cual consiste de dos cadenas: una pesada (115 kDa) y una ligera (35 kDa) la cual posee la actividad catilítica. Esta enzima activa el tripsinógeno reconociendo la secuencia (Asp)4-Lis y cortando en el extremo C-terminal de esta secuencia. Esto la convierte en un reactivo esencial en la producción de proteínas recombinantes en Escherichia coli ya que colocando esta secuencia entre una proteína de fusión y la proteína de interés permitiría la separación de ambas. Para producir la enteroquinasa se utilizará la secuencia de amioácidos del péptido señal de la enzima PelB, una pectato liasa de la bacteria Erwinia carotovora, la cual se encargará de dirigir la expresión al periplasma de Escherichia coli. Se produce aquí ya que es rara la formación de cuerpos de inclusión, favorece la formación de puentes disulfuro para el correcto plegamiento, además hay menos proteínas y esto hace que la fracción sea más pura. Esta proteína se usará en el Laboratorio de Biotecnología de la FCQ para separar proteínas de fusión de las proteínas recombinantes de interé

Metal-Induced Production of a Novel Bioadsorbent Exopolysaccharide in a Native Rhodotorula mucilaginosa from the Mexican Northeastern Region

There is a current need to develop low-cost strategies to degrade and eliminate industrially used colorants discharged into the environment. Colorants discharged into natural water streams pose various threats, including: toxicity, degradation of aesthetics and inhibiting sunlight penetration into aquatic ecosystems. Dyes and colorants usually have complex aromatic molecular structures, which make them very stable and difficult to degrade and eliminate by conventional water treatment systems. The results in this work demonstrated that heavy metal-resistant Rhodotorula mucilaginosa strain UANL-001L isolated from the northeast region of Mexico produce an exopolysaccharide (EPS), during growth, which has colorant adsorption potential. The EPS produced was purified by precipitation and dialysis and was then physically and chemically characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and chemical elemental analysis. Here, the ability of the purified EPS produced to adsorb methylene blue (MB), which served as a model colorant, is studied. MB adsorption by the EPS is found to follow Langmuir Adsorption Isotherm kinetics at 25°C. Further, by calculating the Langmuir constant the adsorption capabilities of the EPS produced by the Rhodotorula mucilaginosa strain UANL-001L is compared to that of other adsorbents, both, microbially produced and from agroindustrial waste. The total adsorption capacity of the EPS, from the Rhodotorula mucilaginosa strain UANL-001L, was found to be two-fold greater than the best bioadsorbents reported in the literature. Finally, apart from determining which heavy metals stimulated EPS production in the strain, the optimal conditions of pH, heavy metal concentration, and rate of agitation of the growing culture for EPS production, was determined. The EPS reported here has the potential of aiding in the efficient removal of colorants both in water treatment plants and in situ in natural water streams