Related topics: cells , genes , amino acids , cancer , cancer cells
Protein
hideProteins (also known as polypeptides) are organic compounds made of amino acids arranged in a linear chain. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids, however in certain organisms the genetic code can include selenocysteine — and in certain archaea — pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by post-translational modification, which alter the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Proteins can also work together to achieve a particular function, and they often associate to form stable complexes.
Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape. Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. Proteins are also necessary in animals' diets, since animals cannot synthesize all the amino acids they need and must obtain essential amino acids from food. Through the process of digestion, animals break down ingested protein into free amino acids that are then used in metabolism.
Proteins were first described and named by the Swedish chemist Jöns Jakob Berzelius in 1838. However, the central role of proteins in living organisms was not fully appreciated until 1926, when James B. Sumner showed that the enzyme urease was a protein. The first protein to be sequenced was insulin, by Frederick Sanger, who won the Nobel Prize for this achievement in 1958. The first protein structures to be solved were hemoglobin and myoglobin, by Max Perutz and Sir John Cowdery Kendrew, respectively, in 1958. The three-dimensional structures of both proteins were first determined by x-ray diffraction analysis; Perutz and Kendrew shared the 1962 Nobel Prize in Chemistry for these discoveries. Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography; the advent of genetic engineering has made possible a number of methods to facilitate purification. Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, and mass spectrometry.
For more information about Protein, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with protein
Researchers find human protein that prevents H1N1 influenza infection
Dec 17, 2009 |
5 / 5 (5) |
1
Howard Hughes Medical Institute researchers have identified a naturally occurring human protein that helps prevent infection by H1N1 influenza and other viruses, including West Nile and dengue virus.
Study reveals H1N1 unexpected weakness
Dec 10, 2009 |
4.8 / 5 (19) |
7
The H1N1 influenza virus has been keeping a secret that may be the key to defeating it and other flu viruses as well.
Splitting fluorescent protein helps image clusters in live cells
Dec 26, 2009 |
3 / 5 (1) |
0
Half a protein is better than none, and in this case, it's way better than a whole one. A Rice University lab has discovered that dividing a particular fluorescent protein and using it as a tag is handy for analyzing the ...
Scientists discover how the brain encodes memories at a cellular level
Dec 23, 2009 |
4.9 / 5 (34) |
17
Scientists at UC Santa Barbara have made a major discovery in how the brain encodes memories. The finding, published in the December 24 issue of the journal Neuron, could eventually lead to the development ...
Study shows a key protein helps control blood pressure
Dec 23, 2009 |
4.5 / 5 (2) |
0
University of Iowa researchers have shown that a protein channel helps nerve sensors in blood vessels keep blood pressure in check. Without the protein channel, known as ASIC2, the sensors are unable to send the brain the ...
New human reproductive hormone could lead to novel contraceptives
Dec 22, 2009 |
4.5 / 5 (4) |
0
(PhysOrg.com) -- Nearly 10 years after the discovery that birds make a hormone that suppresses reproduction, University of California, Berkeley, neuroscientists have established that humans make it too, opening ...
Researchers create new 'smart' nanocapsule delivery system for use in protein therapy
Nanotechnology / Bio & Medicine
Dec 18, 2009 |
5 / 5 (3) |
1
the delivery of healthy proteins directly into human cells to replace malfunctioning proteins — is considered one of the most direct and safe approaches for treating diseases. But its effectiveness has been limited by low ...
Stem-cell activators switch function, repress mature cells
Dec 16, 2009 |
not rated yet |
0
In a developing animal, stem cells proliferate and differentiate to form the organs needed for life. A new study shows how a crucial step in this process happens and how a reversal of that step contributes to cancer.
New protein key for cell proliferation identified
Dec 14, 2009 |
5 / 5 (1) |
0
(PhysOrg.com) -- Researchers at McGill University have identified a protein that plays a key role in cell proliferation and is likely to promote cancer development. The work may lead to the development of new diagnostic tools ...
Scientists crack mystery of protein's dual function
Dec 13, 2009 |
5 / 5 (5) |
0
Researchers at The Scripps Research Institute have solved a 10-year-old mystery of how a single protein from an ancient family of enzymes can have two completely distinct roles in the body. In addition to providing guidance ...
Bacterial protein mimics its host to disable a key enzyme (w/ Video)
Dec 11, 2009 |
5 / 5 (3) |
1
(PhysOrg.com) -- Bacteria use all sorts of cunning to trick hosts into doing their bidding. One con in their bag of tricks: the molecular mimic. In this ruse, bacteria or their agents look for all purposes like some native ...
Synthetic protein mimics structure, function of metalloprotein in nature
Dec 10, 2009 |
5 / 5 (1) |
1
Scientists have designed a synthetic protein that is both a structural model and a functional model of a native protein, nitric-oxide reductase.
Researchers uncover chemical basis for extra 'quality control' in protein production
Dec 09, 2009 |
5 / 5 (1) |
0
December 9, 2009 -Even small errors made by cells during protein production can have profound disease effects, and nature has developed ways to uncover these mistakes and correct them. Though in the case of one essential ...
Newly discovered mechanism allows cells to change state
Dec 09, 2009 |
not rated yet |
0
Cells are not static. They can transform themselves over time — but change can have dangerous implications. Benign cells, for example, can suddenly change into cancerous ones.
Family's inherited condition links prion diseases, Alzheimer's
Medicine & Health / Neuroscience
Dec 09, 2009 |
4.5 / 5 (2) |
0
(PhysOrg.com) -- A laboratory connection between Alzheimer's disease and brain-wasting diseases such as the human form of mad cow disease has moved into the clinic for what is believed to be the first time, manifesting itself ...
