Difference between revisions of "Team:Ecuador/Background"

Cellulose was the most common biopolymer in the world. The primary form in which the material is found is lignocellulotic in trees, however there are other sources such as bacterial cellulose [1].This was first described by Luis Pasteur in the previous century and reported for the first time its use in a Philippine dessert called coconut cream, however, it was not until 1886 when it was reported as a type of cellulose in an acetic fermentation, after being observed as a floating film in a culture medium[2]. In recent years, several studies have been carried out on the usefulness of bacterial cellulose due to its high degree of purity and its simpler structure than that obtained from plants, in addition to the speed of polymer formation, reducing costs and environmental impact in the purification process to eliminate the lignin and other impurities of the material to be applied in the industries[3]. . Bacterial cellulose has been used mainly in the paper industry, in the food for the realization of various desserts and strong dishes and as a material for garment development, due to its great flexibility, it is also impregnated with several nanoparticles to give antimicrobial, antifungal capacities[4]. Its ability to be combined with other proteins gives it the advantage to create new polymers with other desired properties such as bioplastics and drug administrators when combined with therapeutic proteins[5]. The existing biocompatibility between bacterial cellulose and human cells has led to the use of the polymer as a matrix for the regeneration of organs and tissues such as cartilage and skin[6].

Los polipéptidos similares a elastina (Elastin-like polypeptides, ELP) son biopolímeros artificiales genéticamente codificables. Son proteínas elastoméricas formadas por un pentapéptido repetitivo de secuencia Val-Pro-Gly-Xaa-Gly, Xaa puede ser cualquier aminoácido excepto prolina [1]. Las ELP son biopolímeros termoestables cuyas propiedades varian dependiendo de la temperatura, pH o fuerza iónica. Pueden pasar de un estado soluble a uno insoluble y de manera reversible dependiendo de su temperatura de transición (Tt) [2], a temperaturas menores de la Tt ELPs son solubles, pero insoluble cuando la temperatura excede a la Tt. Esta propiedad se mantiene incluso cuando se fusionan con otras proteínas y ha sido usada en purificación de proteínas. El uso de residuos de aminoácidos que contienen grupos susceptibles a la ionización da como resultado un polímero con un Tt regulado por cambios en el pH, además la sustitución del residuo Xaa permite que ELP se diseñe con una Tt deseada [3]. En biomedicina, los ELPs tienen aplicaciones en la liberación específica de medicamentos, en ingeniería de tejidos y medicina regenerativa. Se ha logrado transportar selectivamente medicamentos antineoplásicos hacia los tejidos patológicamente cambiados, permitiendo que los conjugados polímero-fármaco se acumulen en las proximidades del tumor, mostrando una toxicidad menor en comparación con los fármacos de funcionamiento libre [1]. En medicina regenerativa, los ELPs se han empleado como andamios en la regeneración de tejidos, y han mostrado resultados prometedores en tratamientos para el daño del cartílago articular, donde se emplea un hidrogel hecho de ELP en el que contribuyó efectivamente a la producción de una matriz cartilagenosa. Otros estudios demuestran que ELPs conjugados con polímeros como el ácido poliacrílico y polietilenimina puede influir fuertemente en la agregación, morfología y función diferenciada de los hepatocitos in vitro, mostrando la capacidad de utilizar ELP en la regeneración del tejido hepático [1]. Además, ELPs han mostrado resultados prometedores para ser utilizados en la ingeniería de tejidos de la superficie ocular, y en injertos vasculares [4].

The best-folded variants of GFP are widely used as protein fusion labels, but fused proteins can reduce the fold, yield and fluorescence of these GFPs. They perform the process properly, when expressed alone or when it is fused to well-folded proteins; In addition, the resistance of GFP is dependent on the chemistry and thermal denaturation [1]. In this project we will use a GFP super-folder, which is a variation of the green fluorescent protein (GFP). Frequently, wild-type GFP is misfolded when expressed in E. coli and when expressed as fusions with other proteins. Unlike this one, the GFP super-folder contains 'cycle-3' mutations and the 'enhanced GFP' mutations F64L and S65T, giving it a better tolerance to circular permutation, greater resistance to chemical denaturing and better folding kinetics. Therefore, it can be folded correctly even though the fused protein is not well folded. In 2006 it was evidenced through X-ray crystallographic structural analysis, the presence of a network of five-member ion pairs in the GFP superfolder, based on its S30R mutation; and thus improving its folding compared to the GFP reporter.

The discovery of BMPs by Urist in 1965 has been a breakthrough in research that has been shown that the protein is able to stimulate bone production. Due to these properties, this protein is currently used in various fields such as Traumatology, Tissue Engineering and orthopedic surgery in which recombinant human BMP2 (rhBMP2) is used. The implantation of BMP2 in a collagen sponge induces the formation of new bone and can be used as a treatment for certain bone defects. Oral surgery has benefited in particular with the commercialization of this protein, since the use of BMP2 in absorbable collagen sponges has significantly reduced the costs of the interventions and the pain suffered by patients with degenerative disease of the lumbar discotheques.

Cellulose, the most abundant biopolymer and biorenewable compound Earth, is a recalcitrant polysaccharide[1]. Cellulolytic organisms are capable of degrading cellulose which involves excretion of endo- and exo-glucanases as well as glucosidases. Structurally, these enzymes are modular, consisting of a catalytic domain and cellulose-binding domain (CBD), as well as possible ancillary domains[2]. Because of the modules play generally their respective role independently, the CBD has been studied to improve the cellulose degradation as well as to bind other functional proteins. It has been foun that CBD can be found at the N-terminal or at the C-terminal region of these enzymes[4]. In order to evaluate an N-terminal and a C-terminal CBD we chose the domain of Clostridium thermocellum cellulosome-scaffolding protein A (cipA) and the domain of Cellulomonas fimi exoglucanase (Cex). We used the CBDcipA because the high affinity among other CBDs reported by the Imperail College London team (2014). The modules are joined by linkers that are variable in terms of length and amino acid composition. The length ranges from a few to up to 150 amino acids whereas the sequences are rich in proline or/and hydroxyamino acids[3]. Because of the synergistic activity between the catalytic and cellulose-binding domain is dependent of the length and/or linker sequence, we have used their respective endogenous linkers[2].