Cellulases: suppliers of energy and basic compounds, so life
Abstract
Cellulose is the main constituent of plants, serving to maintain their structure. Indeed, it is a major component of tough cell walls that surround plant cells, and is what makes plant stems, leaves, and branches so strong. Cellulose represents the most abundant carbohydrate substance in nature. It is a bio-polymer of glucose units related by β1, 4 glucosidic linkages. Cellulose degradation requires a multi-enzymatic system composed of three enzymes which are respectively: the endoglucanases, the cellobiohydrolases and finally the β-glucosidases. The chemical industry has come under increasing pressure to make chemical production more eco-friendly and independent to fossil resources. The biocatalysts are the best solution given by nature that can be used to improve some biotechnological applications. The use of this renewable material within the packaging industry has gained increasing interest in the last decades. In this research review, we report some peculiar information’s and useful data describing cellulases as biocatalysts, their modulation, implication in a range of metabolic pathways and biotechnological tools.
Keywords
Download Options
Introduction
Catalysis is a process that increases the speed with which a reaction reaches equilibrium. Since the reaction rate is function of the free energy of activation, in which catalyst causes the decrease of the energy barrier, and thus accelerates the catalytic stage as followed in figure 1-A. Meaning this fact, biocatalysts accelerate biochemical reactions that take place inside or outside of a cell to achieve a speed compatible with its normal operation (figure 1-B).Thus, the operation of a cell's life, reproduction requests that all the reactions occur in a coordinated and controlled but also at a sufficient rate. Enzymes are essential actor‟s metabolism. Without them, life as we know it would not be possible [1].
The biocatalysts operate on various types of mechanisms that fall into six categories as described in table 1. (1) Acid-base catalysis; (2) Covalent catalysis; (3) Catalysis by metal ion; (4) Electrostatic catalysis; (5) Catalysis by proximity effect and guidance and (6) Catalysis by preferential binding to the transition state complex (table 1). Furthermore, and in addition to their vital character, enzymes have begun in recent decades to be very effective tools in many areas of application such as cosmetic, pharmaceutical, para pharmaceutical, therapeutic, food, etc [1, 2].
In this research review, we will focus on cellulases that are encoding acid-base catalytic reaction. For this, it is best to start by introducing the natural substrate of this category of biocatalysts which is cellulose.
Conclusion
Cellulases have evolved to be the most powerful and prevalent biomass degrading system in nature, exhibiting the turnover of lignocellulosic material on Earth. Given their significant activity and ability to be readily produced at high titers on the industrial scale, cellulases are considered as an excellent solution and strategy for biotechnological applications.
In another hand, cellulases, some of which remain to be discovered, work in concert to accomplish one of the most important processes in nature, namely the turnover of cellulose. This process is of paramount importance in the global carbon cycle and may become one of the most biotechnological important enzymatic reactions given the desperately needed drive toward a renewable energy-based global society.
As reported in this case, significant strides in our fundamental understanding of cellulase action have been made in the past several decades, especially driven by the structural biology efforts starting 20 years ago. However, we will strive to enhance and ameliorate the level of exploration of these natural capacities in order to improve the Human life.