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
1930s drug slows tumor growth
Medicine & Health / Medications
Nov 06, 2009 |
4.6 / 5 (8) |
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Drugs sometimes have beneficial side effects. A glaucoma treatment causes luscious eyelashes. A blood pressure drug also aids those with a rare genetic disease. The newest surprise discovered by researchers at the Johns ...
Polycystins : proteins that regulate the cellular barometer
Nov 05, 2009 |
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What is the role of proteins called polycystins in patients with polycystic kidney disease? A team of researchers from CNRS and INSERM, led by Eric Honoré from the Institut de Pharmacologie Moléculaire ...
Researchers pioneer kidney disease prediction method
Nov 05, 2009 |
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(PhysOrg.com) -- A study into the relationship between antibodies and proteins in people with Lupus could mean earlier diagnosis of kidney disease in such patients, and lead the way for earlier diagnoses for ...
Scientists reveal a new mechanism that increases atherosclerosis in mice
Nov 05, 2009 |
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(PhysOrg.com) -- For all the good it does, a liver protein that senses and gets rid of drugs and pollutants from our body has a downside. For the first time, it has been shown that when it is chronically activated, ...
Researchers identify drug candidate for treating spinal muscular atrophy
Nov 04, 2009 |
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A chemical cousin of the common antibiotic tetracycline might be useful in treating spinal muscular atrophy (SMA), a currently incurable disease that is the leading genetic cause of death in infants. This is the finding of ...
New discoveries in the yeast Saccharomyces cerevisiae
Nov 04, 2009 |
4 / 5 (1) |
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Researchers at UAB in collaboration with the University of Stellenbosch, South Africa, have discovered the structure of the PPC descarboxilase (PPCDC) enzyme present in the yeast Saccharomyces cerevisiae, a very important ...
NIST quantifies low levels of 'heart attack risk' protein
Chemistry / Analytical Chemistry
Nov 04, 2009 |
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Searching for a needle in a haystack may seem futile, but it's worth it if the needle is a hard-to-detect protein that may identify a person at high risk of a heart attack circulating within a haystack of ...
Scientists obtain clearer view of how eye lens proteins are sorted
Nov 03, 2009 |
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New research reveals how proteins that are critical for the transparency of the eye lens are properly sorted and localized in membrane bilayers. The study, published by Cell Press in the November 3rd issue of Biophysical Jo ...
Study sheds light on evolution of human complexity
Nov 03, 2009 |
3.3 / 5 (6) |
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(PhysOrg.com) -- A painstaking analysis of thousands of genes and the proteins they encode shows that human beings are biologically complex, at least in part, because of the way humans evolved to cope with redundancies arising ...
New findings bring hope for possible Parkinson's disease cure
Nov 03, 2009 |
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Researchers at Iowa State University have found an essential key to possibly cure Parkinson's disease and are looking for others.
Two genes cooperate to cause aggressive leukemia
Nov 03, 2009 |
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Two genes, each one of which is known to cause cancer on its own, together can lead to aggressive leukaemia. This is the conclusion from new research carried out on gene-modified mice at the Sahlgrenska Academy at the University ...
Gene Increases Susceptibility to Post-Traumatic Stress, Researchers Find
Medicine & Health / Psychology & Psychiatry
Nov 02, 2009 |
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(PhysOrg.com) -- A gene variant makes people who experienced trauma as children or adults more susceptible to post-traumatic stress disorder (PTSD), Yale researchers have found.
New activity found for a potential anti-cancer agent
Nov 02, 2009 |
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Pateamine A (PatA), a natural product first isolated from marine sponges, has attracted considerable attention as a potential anti-cancer agent, and now a new activity has been found for it, which may reveal yet another anti-cancer ...
Scientists Propose New Explanation for Flu Virus Antigenic Drift
Oct 29, 2009 |
4.3 / 5 (3) |
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(PhysOrg.com) -- Influenza viruses evade infection-fighting antibodies by constantly changing the shape of their major surface protein. This shape-shifting, called antigenic drift, is why influenza vaccines ...
Two-pronged protein attack could be source of SARS virulence
Oct 29, 2009 |
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Ever since the previously unknown SARS virus emerged from southern China in 2003, University of Texas Medical Branch at Galveston virologists have focused on finding the source of the pathogen's virulence — its ability to ...
