Related topics: proceedings of the national academy of sciences , genes , protein
Enzyme
hideEnzymes 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).
For more information about Enzyme, read the full article at
Wikipedia.
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News tagged with enzyme
Making New Enzymes to Engineer Plants for Biofuel Production
Dec 21, 2009 |
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(PhysOrg.com) -- Brookhaven scientists have created a new enzyme with the potential to interfere with a key cell-wall component in plants, possibly leading to plants that are easier to "digest" and convert ...
Scientists take a step towards uncovering the histone code
Dec 20, 2009 |
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Researchers at Emory University School of Medicine have determined the structures of two enzymes that customize histones, the spool-like proteins around which DNA coils inside the cell.
Research project yields better understanding of the defective protein that causes cystic fibrosis
Dec 18, 2009 |
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A team of researchers studying the protein that, when defective or absent, causes cystic fibrosis (CF) has made an important discovery about how that protein is normally controlled and under what circumstances ...
Blood Enzyme Could Help Realize Clean Coal
Dec 03, 2009 |
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(PhysOrg.com) -- An enzyme in our blood that enables our lungs to exhale carbon dioxide could be the key to isolating carbon dioxide emissions from coal plants in order to store them safely underground. A ...
Kangaroos may hold skin cancer cure: study
Nov 30, 2009 |
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Kangaroos may provide the key to a potential treatment to prevent skin cancer, Australian scientists said Monday.
The hidden lives of proteins
Dec 02, 2009 |
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An important Brandeis study appearing in the December 3 issue of Nature raises the curtain on the hidden lives of proteins at the atomic level. The study reports that for the first time, researchers used x ...
Scientists show how ubiquitin chains are added to cell-cycle proteins
Dec 02, 2009 |
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Researchers from the California Institute of Technology (Caltech) have been able to view in detail, and for the first time, the previously mysterious process by which long chains of a protein called ubiquitin ...
Researchers identify a scaffold regulating protein disposal
Dec 11, 2009 |
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How does a cell manage to identify and degrade the diverse types of defective proteins and thus protect the body against serious diseases? The researchers Sabine C. Horn, Professor Thomas Sommer, Professor Udo Heinemann and ...
Study helps advance heart-related research
Dec 04, 2009 |
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Using a new mathematical model of heart cells, University of Iowa investigators have shown how activation of a critical enzyme, calmodulin kinase II (CaM kinase), disrupts the electrical activity of heart cells.
Long-term physical activity has an anti-aging effect at the cellular level
Nov 30, 2009 |
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Intensive exercise prevented shortening of telomeres, a protective effect against aging of the cardiovascular system, according to research reported in Circulation: Journal of the American Heart Association.
2 heads better than 1 in new antibiotic method
Dec 03, 2009 |
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An antibiotic that binds to a well-established target in a novel and unexpected way could be the inspiration for designing new, more potent antibacterial drugs.
