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
Study reveals H1N1 unexpected weakness
Dec 10, 2009 |
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The H1N1 influenza virus has been keeping a secret that may be the key to defeating it and other flu viruses as well.
New protein key for cell proliferation identified
Dec 14, 2009 |
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(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 |
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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 |
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(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 |
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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 |
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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 |
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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 |
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(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 ...
Researchers tackle protein mechanisms behind limb regeneration
Dec 14, 2009 |
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The most comprehensive study to date of the proteins in a species of salamander that can regrow appendages may provide important clues to how similar regeneration could be induced in humans.
Study explores 'garbage disposal' role of VCP and implications for degenerative disease
Dec 14, 2009 |
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It's important to finish what you start, say Jeong-Sun Ju and researchers from Washington University School of Medicine, St. Louis. In the December 14, 2009 issue of the Journal of Cell Biology, Ju et al. ...
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 ...
Reaching the summit of protein dynamics
Dec 10, 2009 |
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Understanding the incredibly speedy atomic mechanisms at work when a protein transitions from one shape to another has been an elusive scientific goal for years, but an essential one for elucidating the full ...
Drug kills cells through novel mechanism
Dec 10, 2009 |
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MIT and Boston University researchers have discovered that the drug hydroxyurea kills bacteria by inducing them to produce molecules toxic to themselves — a conclusion that raises the possibility of finding ...
Researchers discover a way to strengthen proteins
Dec 10, 2009 |
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Proteins, which perform such vital roles in our bodies as building and maintaining tissues and regulating cellular processes, are a finicky lot. In order to work properly, they must be folded just so, yet many proteins readily ...
Potential new heart attack biomarker uncovered
Dec 10, 2009 |
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Though they remain a leading killer, heart attacks can be effectively treated provided they can be rapidly diagnosed following initial onset of symptoms. In a study appearing in this month's Molecular and Cellular Proteomics, resear ...
