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
Clinical trials of spray-on skin to start in US
Nov 24, 2009 |
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(PhysOrg.com) -- Clinical trials comparing a spray-on skin product with skin grafts will start in the US in December. The trials, which are partly funded by a US army grant of $1.4 million, will last about a year and will ...
An end to sleep problems? Researchers discover enzyme behind effects of sleep deprivation
Nov 26, 2009 |
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There is hope for those who miss one night too many or whose children keep them up at night. The unwelcome effects of a bad night's sleep - forgetfulness, impaired mental performance - can be dealt with by reducing the concentration ...
Cancer metabolism discovery uncovers new role of IDH1 gene mutation in brain cancer
Nov 22, 2009 |
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Agios Pharmaceuticals today announced that its scientists have established, for the first time, that the mutated IDH1 gene has a novel enzyme activity consistent with a cancer-causing gene, or oncogene. This breakthrough ...
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Knockouts in human cells point to pathogenic targets
Nov 26, 2009 |
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(PhysOrg.com) -- Whitehead researchers have developed a new approach for genetics in human cells and used this technique to identify specific genes and proteins required for pathogens.
Scientists reveal 'protector' gene behind 50-fold increase in number of bowel tumours
Nov 26, 2009 |
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(PhysOrg.com) -- Cancer Research UK scientists have shown that deleting a single gene can increase the average number of tumours in the bowel by 50-fold, according to research published in PNAS today.
Whiteflies sabotage alarm system of plant in distress
Nov 26, 2009 |
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(PhysOrg.com) -- When spider mites attack a bean plant, the plant responds by producing odours which attract predatory mites. These predatory mites then exterminate the spider mite population, thus acting ...
Physicians Explore Link Between Vitamin D Deficiency and Hypertension
Nov 25, 2009 |
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(PhysOrg.com) -- Drs. William White and Pooja Luthra at the University of Connecticut Health Center are investigating a possible link between vitamin D deficiency and high blood pressure.
Tissue tension regulates tumor progression
Nov 23, 2009 |
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(PhysOrg.com) -- UCSF scientists have shown for the first time that the rigidity of a tissue can induce cancer. The research team identified an enzyme that is crucial for regulating tissue stiffness and demonstrated that ...
Bioengineers succeed in producing plastic without the use of fossil fuels
Nov 23, 2009 |
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A team of pioneering South Korean scientists have succeeded in producing the polymers used for everyday plastics through bioengineering, rather than through the use of fossil fuel based chemicals. This groundbreaking research, ...
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