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
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News tagged with enzyme
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(PhysOrg.com) -- Not too long ago, it seemed that ethanol production was the wave of the future. The use of trash, wood chips or different types of plants -- usually grass or corn -- to make ethanol was considered ...
Scientists successfully reprogram blood cells
Nov 09, 2009 |
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Researchers have transplanted genetically modified hematopoietic stem cells into mice so that their developing red blood cells produce a critical lysosomal enzyme -preventing or reducing organ and central nervous system damage ...
Venomous bite: Harmless digestive enzyme evolved into venom in two species
Oct 29, 2009 |
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(PhysOrg.com) -- Biologists have shown that independent but similar molecular changes turned a harmless digestive enzyme into a toxin in two unrelated species -- a shrew and a lizard -- giving each a venomous ...
Researchers unravel mystery behind long-lasting memories
Medicine & Health / Neuroscience
Aug 11, 2009 |
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A new study by researchers at Wake Forest University School of Medicine may reveal how long-lasting memories form in the brain.
Early evolution maximized the 'spellchecking' of protein sequences
Aug 06, 2009 |
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As letters of the alphabet spell out words, when amino acids are linked to one another in a particular order they "spell out" proteins. But sometimes the cell machinery for building proteins in our bodies makes a mistake ...
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Jul 20, 2009 |
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usually mere sugar pills designed to represent "no treatment" in a clinical treatment study. The effectiveness of the actual medication is compared with the placebo to determine if the medication works.
Scientists create new enzymes for biofuel production
Mar 23, 2009 |
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Researchers at the California Institute of Technology (Caltech) and world-leading gene-synthesis company DNA2.0 have taken an important step toward the development of a cost-efficient process to extract sugars ...
Discovery fleshes out metabolism of key environmental and energy bacteria
Feb 02, 2009 |
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An international collaboration of researchers has discovered a new enzyme in a species of bacteria with potential environmental cleanup and energy roles. This is the first multi-protein enzyme of its kind. ...
Scientists develop first examples of RNA that replicates itself indefinitely
Jan 09, 2009 |
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Now, a pair of Scripps Research Institute scientists has taken a significant step toward answering that question. The scientists have synthesized for the first time RNA enzymes that can replicate themselves without the help ...
Kangaroos may hold skin cancer cure: study
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Kangaroos may provide the key to a potential treatment to prevent skin cancer, Australian scientists said Monday.
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 ...
Tiny particles can deliver antioxidant enzyme to injured heart cells
Nov 16, 2009 |
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Researchers at Emory University and the Georgia Institute of Technology have developed microscopic polymer beads that can deliver an antioxidant enzyme made naturally by the body into the heart.
Novel mouse gene reduces major pathologies associated with Alzheimer's disease
Medicine & Health / Neuroscience
Nov 11, 2009 |
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A new study reveals that a previously undiscovered mouse gene reduces the two major pathological perturbations commonly associated with Alzheimer's disease (AD). The research, published by Cell Press in the November 12 issue ...
Researchers reconstitute enzyme that synthesizes cholesterol drug lovastatin
Nov 03, 2009 |
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Researchers from the UCLA Henry Samueli School of Engineering and Applied Science have for the first time successfully reconstituted in the laboratory the enzyme responsible for producing the blockbuster cholesterol-lowering ...
Spinal cord regeneration enabled by stabilizing, improving delivery of scar-degrading enzyme
Nov 02, 2009 |
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Researchers have developed an improved version of an enzyme that degrades the dense scar tissue that forms when the central nervous system is damaged. By digesting the tissue that blocks re-growth of damaged ...
