Lechuga Fernández, Inmaculada
Chitin and chitosan are biocompatible, biodegradable, non-toxic, have antimicrobial properties and the ability to absorb metal ions (Islam et al., 2017). Its water-retaining and moisturizing properties make it useful in the cosmetic industry, while chitosan's high chemical reactivity makes it useful in drug conjugates for cancer therapies. Currently the main application of these polysaccharides is being used as biomaterials and as an alternative to synthetic polymers in industry. Chitosan can be formed into membranes and is used in tissue engineering applications, its gels, powders, and films are useful for encapsulation, membrane barriers, contact lenses, and cell cultures.
Chitin and chitosan can be obtained chemically by extracting them from biowaste from seafood factories (Islam et al., 2017). The shells are crushed to smaller sizes and minerals such as calcium carbonate are removed by extraction with hydrochloric acid. Protein extraction is performed by treating it with a dilute sodium hydroxide solution. The resulting chitin obtained is then deacetylated in 40-45% sodium hydroxide at high temperatures (160°C) for 1-3 hours in the absence of oxygen followed by purification procedures to form chitosan. The degree of acetylation depends on the concentration of NaOH, the reaction temperature and the time. Depending on the production method, the deacetylation ranges are from 56 to 99%. Although chemically chitosan can be obtained with high deacetylation rates, some of its disadvantages are time-consuming production, undesirable side reactions, and randomness of chemical reactions, giving irregular deacetylation patterns. The great advantage of the chemical synthesis of chitosan is that it allows us to produce it industrially in large quantities. On the other hand, biotechnologically, chitosan can be obtained by producing it from the cell walls of fungi. The extraction bioprocess, unlike the chemical method, does not require high temperatures or strong alkaline solutions, and the chitosan-producing species have approximately the same degree of deacetylation and lower viscosity than chitosan produced from crustacean chitin. Another alternative to produce chitosan biologically is to use chitinases and deacetylases that give products with more homogeneous deacetylation patterns and oligomers of controlled size. The main drawback of using enzymes to convert chitin to chitosan is the difficulties in producing it on a large scale (Grifoll-Romero et al., 2018).
This project studies the binding mechanism of a family 4 carbohydrate esterase to its substrates following one of the research lines of the biochemistry laboratory, which is dedicated to the use of enzymes active on carbohydrates to obtain high-quality products. worth. The main interest here is to use family 4 carbohydrate esterases to obtain chitin oligomers with known deacetylated patterns.