Introduction
Enzymes are proteins that catalyze (i.e. accelerate)chemical reactions. In these reactions, the molecules at the beginning of theprocess are called substrates, and the enzyme converts these into differentmolecules, the products. Almost all processes in the cell need enzymes in orderto occur at significant rates. Since enzymes are extremely selective for theirsubstrates and speed up only a few reactions from among many possibilities, theset of enzymes made in a cell determines which metabolic pathways occur in thatcell.
Like all catalysts, enzymes work by lowering theactivation energy for a reaction and thus dramatically accelerating the rate ofthe reaction. By binding the transition-state conformation of thesubstrate/product molecules, the enzyme distorts the bound substrate(s) intotheir transition state form, thereby reducing the amount of energy required tocomplete the transition. Most natural enzymes accelerate their reaction manymillions of times faster compared to the uncatalyzed reaction. As with allcatalysts, enzymes are not consumed by the reactions they catalyze, nor do theyalter the equilibrium of these reactions. However, enzymes do differ from mostother catalysts by being much more specific. Enzymes are known to catalyzeabout 4,000 biochemical reactions. Not all biochemical catalysts are proteins,since some RNA molecules called ribozymes can also catalyze reactions.
Some enzymes are used commercially, for example, inthe synthesis of antibiotics. In addition, some household products use enzymesto speed up biochemical reactions (e.g., enzymes in biological washingpowders break down protein or fat stains on clothes; enzymes in steaktenderizers break down long meat proteins, making them easier to chew).
About the Authors
Theauthors are associated with the Department of Clothing & Textiles, G.B.P.U.A & T,Pantnagar, Udham Singh Nagar, India.
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