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

Single-atom nanozymes

Nanozymes are catalytic nanomaterials with enzyme-like characteristics that have attracted enormous recent research interest. The catalytic nanomaterials offer unique advantages of low cost, high stability, tunable catalytic ...

Gut bacteria influence movement in flies

Warm, protected, and full of nutrients—the tiny intestines of a fruit fly are a perfect habitat for some bacteria. These bacteria, in turn, help the fly break down and digest food, keeping the insect's metabolism running ...

New CRISPR tool opens up more of the genome for editing

The genome editing system CRISPR has become a hugely important tool in medical research, and could ultimately have a significant impact in fields such as agriculture, bioenergy, and food security.

Engineering a plastic-eating enzyme

Scientists have engineered an enzyme which can digest some of our most commonly polluting plastics, providing a potential solution to one of the world's biggest environmental problems.

Directed evolution opens door to new antibiotics

In the ongoing arms race with humans and their antibiotics on one side, and bacteria with their ability to evolve defenses to antibiotics on the other, humans have enlisted a new ally—other bacteria.

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Enzyme

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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