Related topics: protein · cells · bacteria · chemical reactions · cancer

Heterogeneous catalyst goes enzymatic

What if there were no tunnels in the Swiss Alps? Anyone trying to travel through them would have to go up and down hills and zigzag around the ranges. A lot more energy and time is saved by passing through a tunnel than climbing ...

Biochemists discover an enzyme to stop cell death

RUDN biochemists found out that apoptosis (programmed cell death) can be regulated using the EndoG enzyme. The discovery will lead to a better understanding of cell and tissue protection mechanisms. The results of the study ...

Researchers characterize molecular scissors for plastic waste

A research team from the University of Greifswald and Helmholtz-Zentrum-Berlin (HZB) has solved the molecular structure of the enzyme MHETase at BESSY II. MHETase was discovered in bacteria, and together with a second enzyme, ...

Everyday enzymes, now grown in plants

The jeans you wear, the orange juice you drink, the laundry detergent you use: None would be possible without the activity of enzymes. Currently the enzymes used in industry are produced through an expensive, laborious process, ...

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Enzymes are biomolecules that catalyze (i.e., increase the rates of) chemical reactions. Nearly all known enzymes are proteins. However, certain RNA molecules can be effective biocatalysts too. These RNA molecules have come to be known as ribozymes. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Like all catalysts, enzymes work by lowering the activation energy (Ea or ΔG‡) for a reaction, thus dramatically increasing the rate of the reaction. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions. A few RNA molecules called ribozymes catalyze reactions, with an important example being some parts of the ribosome. Synthetic molecules called artificial enzymes also display enzyme-like catalysis.

Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Activity is also affected by temperature, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins, making the meat easier to chew).

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