Enzymes- An Introduction
Enzymes are amino acid polymers whose structures derive their definition from the genetic code stored in the DNA that determines the amino acid sequence of a protein, which defines the primary structure of the protein. This primary structure aids in directing the protein self-assemble into three structures namely secondary, tertiary, and quaternary, which are responsible for the three-dimensional, active protein conformation. This self- assembly process is called "protein folding" and brings all the amino acids of the protein polymer together so that a catalytic active center is formed.
Enzymes function as stereospecific catalysts to form the cell system all the while acting as mediators for all chemical reactions occurring in the living system. Enzymes along with other proteins aid in repair, duplication, and information expression in a cell's DNA.
Enzymes hydrolyze proteins and other polysaccharides and also serve as biocatalysts in many chemical reactions. Enzymes have been of primary importance since the nineteenth century serving as powerful biocatalysts in cell metabolic pathways.
Enzymes in Systems Biology
Metabolic engineering analyzes protein overexpression or the up and down regulation of proteins, which achieves catalytic activity to enhance the substrate flow to form the desired end product. Metabolic pathways in microorganisms help in identifying a weak or missing link between the substrate and the end product and could potentially lead to genes insertion, which generates an enzyme pathway or a missing enzyme, when expressed.
A good example is the xylose kinase gene insertion into yeast or into E.coli to generate organisms that are capable of fermenting glucose and xylose to ethanol. This process increases the ethanol yield from crops, grass, or trees by 50 percent.
Alternatively, substrate carbon can be directed to the specific product by eliminating or blocking metabolic pathways, which direct certain substrates to other products. A good example is a bacterium, which produces two organic acid types, namely acetate and lactate-- where only one is the desired end product. Knocking out acetate pathway leads to more lactate or vice versa.
Enzyme progress in biotechnology has resulted in gene shuffling, which achieved success in random. Recombinant techniques were used to randomly cut and recombined genes. Under specific growth conditions, microbial cells that contained the shuffled genes were selected, propagated, and then altered. This cycle is repeated until the desired product is obtained. Enzymes and gene shuffling, under the direction of a scientist, have resulted in an evolution with potential economic advantages; hence the process became to be known as directe evolution.
Enzymes and Industrial Applications
Industrial enzymes are derived from microorganisms. Before the concept of molecular biology evolved, the DNA of microorganisms was altered randomly by treating the microbes with mutagens or radiation. This process hoped to isolate survivors with enhanced propensity to produce the desired end product. One such example includes: the
Rut C30 strain of the fungi Trichoderma reesei was generated in this manner by cellulose hydrolysis to produce cellulases. Once molecular biology took shape, microorganisms were altered genetically to produce proteins. Also, enzymes with special activities were obtained either by biocatalysis combination or site-directed mutagenesis.
Enzymes In Vivo
In in vivo process, enzymes catalyze a series of reactions predominantly in an aqueous environment. Reversibility is exhibited in major portions of the reactions. reactions are primarily directed to the specific products for industrial applications by growing microorganisms so that the environmental conditions and metabolic pathways direct intermediates flux to the desired end product. This is either achieved by a gene modification in the organism to add an enzyme pathway or a missing enzyme or by enhancing the activity of an enzyme present in the microbe.
Enzymes In Vitro
In in vitro process, the catalysis of soluble enzymes occurs in both aqueous and non-aqueous environments for important industrial reactions. Industrial enzymes are used either in an immobilized or soluble form. In heterogeneous reactions, soluble enzymes are used in a batch reactor. Example include: lipases and proteases in laundry detergents-- where laundry acts as a solid matrix-- and in cheese making--where colloidal proteins are modified by proteases to form a solid. In homogenous reactions, immobilized enzymes are used. Example includes the glucose isomerization to fructose.
Enzymes, especially immobilized enzymes, have achieved a 40 million worldwide sale till date. Immobilized enzymes that contain fumarase, penicillin acylase, and β-galactosidase
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