Related topics: proceedings of the national academy of sciences , cells , genes
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.
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News tagged with protein
Biologists discover bacterial defense mechanism against aggressive oxygen
6 hours ago |
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Bacteria possess an ingenious mechanism for preventing oxygen from harming the building blocks of the cell. This is the new finding of a team of biologists that includes Joris Messens of VIB, a life sciences research institute ...
Scientists identify DNA that regulates antibody production
10 hours ago |
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(PhysOrg.com) -- When foreign invaders trip the immune system’s alarm, antibodies need to be specially sculpted to attack them head on. New research now shows that gene segments called enhancers control the reshuffling of ...
Researchers find new piece of BSE puzzle
14 hours ago |
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A new treatment route for bovine spongiform encephalopathy (BSE) and its human form Creutzfeldt Jakob disease (CJD) could be a step closer based on new results from scientists at the University of Leeds. The team has found ...
Saving the single cysteine: new antioxidant system found (w/ Video)
Nov 19, 2009 |
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(PhysOrg.com) -- We've all read studies about the health benefits of having a life partner. The same thing is true at the molecular level, where amino acids known as cysteines are much more vulnerable to damage when single ...
Scientists unlock clues for tailoring corn plant for food, energy needs
Nov 19, 2009 |
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(PhysOrg.com) -- Scientists have long known that the offspring of two inbred strains tend to be superior to both their parents. Now, a team of researchers including a University of Florida geneticist has discovered clues ...
Let them eat snail
Nov 19, 2009 |
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A nutritionist in Nigeria says that malnutrition and iron deficiency in schoolchildren could be reduced in her country by baking up snail pie. In a research paper to be published in the International Journal of Food Safety, Nu ...
On the trail of a vaccine for Lyme disease: Researchers target tick saliva
Nov 19, 2009 |
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A protein found in the saliva of ticks helps protect mice from developing Lyme disease, Yale researchers have discovered. The findings, published in the November 19 issue of Cell Host & Microbe, may spur d ...
Saliva proteins change as women age
Nov 18, 2009 |
4 / 5 (1) |
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In a step toward using human saliva to tell whether those stiff joints, memory lapses, and other telltale signs of aging are normal or red flags for disease, scientists are describing how the protein content ...
Small nanoparticles bring big improvement to medical imaging
Nanotechnology / Bio & Medicine
Nov 18, 2009 |
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If you're watching the complex processes in a living cell, it is easy to miss something important—especially if you are watching changes that take a long time to unfold and require high-spatial-resolution ...
Magnetic Nanotags Spot Cancer in Mice Earlier Than Current Methods
Nanotechnology / Bio & Medicine
Nov 17, 2009 |
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(PhysOrg.com) -- Searching for biomarkers that can warn of diseases such as cancer while they are still in their earliest stage is likely to become far easier thanks to an innovative biosensor chip developed by Stanford University ...
Imaging study shows HIV particles assembling around its genome
Medicine & Health / HIV & AIDS
Nov 17, 2009 |
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(PhysOrg.com) -- The genesis of one the planet's most lethal viruses, HIV, has been caught on tape. New imaging experiments show individual HIV genomes -- strands of RNA — docking on the inner membrane of an infected cell ...
Researchers Identify Gene Mutations Underlying Risk for Most Common Form of Parkinson's Disease
Nov 17, 2009 |
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(PhysOrg.com) -- Two genes containing mutations known to cause rare familial forms of parkinsonism are also associated with the more common, sporadic form of the disease where there is no family history, researchers have ...
Researchers discover Hedgehogs could play a role in treating osteoarthritis
Nov 17, 2009 |
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(PhysOrg.com) -- Researchers at the University of Toronto and the Hospital for Sick Children (SickKids) have found a pharmacological approach to treating the disease. The study is published in the November 15 advance online ...
Wistar researchers show targeting 'normal' cells in tumors slows growth
Nov 16, 2009 |
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Targeting the normal cells that surround cancer cells within and around a tumor is a strategy that could greatly increase the effectiveness of traditional anti-cancer treatments, say researchers at The Wistar Institute.
Researchers find potential treatment for Huntington's disease (w/ Video)
Nov 15, 2009 |
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Investigators at Burnham Institute for Medical Research, the University of British Columbia's Centre for Molecular Medicine and Therapeutics and the University of California, San Diego have found that normal synaptic activity ...
