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.
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News tagged with protein
New human reproductive hormone could lead to novel contraceptives
10 hours ago |
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(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 ...
Nut Roasting Benefits: Antioxidant levels of nuts increases after roasting
5 hours ago |
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The chemical reaction that darkens a batch of roasting peanuts also boosts the amount of antioxidants they contain, according to a new study in the journal Food Chemistry.
Protein link may be key to new treatment for aggressive brain tumor
11 hours ago |
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Biomedical researchers at the University of Central Florida have found a protein that could hold the key to treating one of the most common and aggressive brain tumors in adults.
Team makes breakthrough demonstration of pH-regulating protein
11 hours ago |
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Researchers have identified the protein mechanism that senses bicarbonate fluctuations and adjusts blood pH levels.
Understanding relationship of proteins, fatty acids could help treat diseases
9 hours ago |
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(PhysOrg.com) -- It's widely understood that eating a diet high in saturated fats increases the risk for a long list of chronic and deadly diseases, including diabetes and coronary heart disease. Understanding ...
New insight in nerve cell communication
Medicine & Health / Neuroscience
11 hours ago |
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Communication between nerve cells is vital for our bodies to function. Part of this communication happens through vesicles containing signalling molecules called neurotransmitters. The vesicle fuses with the ...
What is the function of the protein CD20?
19 hours ago |
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Antibodies directed against the protein CD20, which is expressed by immune cells known as B cells, are used to treat B cell non-Hodgkin lymphoma and rheumatoid arthritis. Despite this, the function of CD20 has not been determined. ...
Replicating Climate Change to Forecast its Effects
Dec 17, 2009 |
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(PhysOrg.com) -- Agricultural Research Service (ARS) scientists are replicating the effects of climate change to see what the future holds for soybeans, wheat and the soils where they grow.
Proline Repeats in Protein Help Grow Tooth Enamel (w/ Podcast)
Dec 21, 2009 |
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(PhysOrg.com) -- A simple amino acid that is repeated in the center of proteins found in tooth enamel makes teeth stronger and more resilient, according to new research at the University of Illinois at Chicago.
Protein that represses genes may play role in cell growth
Dec 21, 2009 |
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(PhysOrg.com) -- A Cornell study shows the protein not only activates some genes involved in the regulation of cell growth and signaling, but also may play a role in preventing cancers by inhibiting cell proliferation.
Researchers find human protein that prevents H1N1 influenza infection
Dec 17, 2009 |
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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.
IKK may act as both inhibitor and promoter of Huntington's disease
Dec 21, 2009 |
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The kinase IKK phosphorylates the protein mutated in Huntington's disease to promote its removal and neuron survival, but IKK may be a double-edged sword that increases neurotoxicity in later stages of the disease. The study, ...
Researchers create new 'smart' nanocapsule delivery system for use in protein therapy
Nanotechnology / Bio & Medicine
Dec 18, 2009 |
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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 |
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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.
Large-scale sequencing: The future of genomic sciences?
Dec 17, 2009 |
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Scientists can gain insights into new ways to use microorganisms in medicine and manufacturing through a coordinated large-scale effort to sequence the genomes of not just individual microorganisms but entire ecosystems, ...
