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

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.

Vitamins A and C help erase cell memory

Vitamins A and C aren't just good for your health, they affect your DNA too. Researchers at the Babraham Institute and their international collaborators have discovered how vitamins A and C act to modify the epigenetic 'memory' ...

A tangled web: Teasing out the effects of CBD on canine seizures

Cannabidiol, popularly known as CBD, gained mainstream fame for treating seizures with a strain of hemp called "Charlotte's Web." It was named for Charlotte Figi, a child with Dravet syndrome whose family was so desperate ...

Scientists persuade nature to make silicon-carbon bonds

A new study is the first to show that living organisms can be persuaded to make silicon-carbon bonds—something only chemists had done before. Scientists at Caltech "bred" a bacterial protein to make the man-made bonds—a ...

New technique offers glimpse at human evolution in action

In research published in Science, a Stanford-led international team used a new analytic technique to map recent evolution. The technique relies exclusively on the DNA sequences of modern humans, yet it can reveal rapid ...

Surprising enzymes found in giant ocean viruses

A new study led by researchers at Woods Hole Oceanographic Institution (WHOI) and Swansea University Medical School furthers our knowledge of viruses—in the sea and on land— and their potential to cause life-threatening ...

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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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