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

Enzyme in human salivary microbes decomposes PET-based plastics

Human saliva may contain an enzyme which can decompose the plastic polyethylene terephthalate (PET). Researchers found the promising enzyme, a hydrolase, in a database containing human metagenome samples. As they report in ...

The new heroics of RNA in cell differentiation

Scientists are increasingly learning of new reasons to appreciate RNA, and the glycolytic enzyme ENO1 seems to have provided yet another in new research from EMBL this week, as published in Molecular Cell.

How protists crack the walls of algae

A team of researchers led by Dr. Sebastian Hess from the University of Cologne's Institute of Zoology has studied the expression of carbohydrate-active enzymes in the unicellular organism Orciraptor agilis by RNA sequencing. ...

New processing technique could make potatoes healthier

Researchers announced early tests of a new potato processing technique designed to make our bodies digest potato starch more slowly. Laboratory demonstrations show that the approach blocks certain digestive enzymes from reaching ...

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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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