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
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Medicine & Health / Neuroscience
7 hours ago |
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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 ...
Why cancer cells just won't die (w/ Video)
4 hours ago |
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When cells experience DNA damage, they'll try to repair it. But if that fails, the damaged cells are supposed to self-destruct, a process called apoptosis. A cancer researcher at Robarts Research Institute at The University ...
Women with breast cancer who consume soy food have lower risk of cancer recurrence
23 hours ago |
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Although there is a concern regarding the safety of soy food consumption among breast cancer survivors, researchers have found that women in China who had breast cancer and a higher intake of soy food had an associated lower ...
Scientists reveal key structure from ebola virus
23 hours ago |
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Scientists at The Scripps Research Institute have determined the structure of a critical protein from the Ebola virus, which, though rare, is one of the deadliest viruses on the planet killing between 50 and 90 percent of ...
Transcription factors guide differences in human and chimp brain function
Dec 07, 2009 |
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Humans share at least 97 percent of their genes with chimpanzees, but, as a new study of transcription factors makes clear, what you have in your genome may be less important than how you use it.
Undergrad researchers lay groundwork for drug addiction remedy
Dec 08, 2009 |
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Sarah Steele and Langtian "Ren" Yuan were both self-admittedly inexperienced Duke freshmen in the spring of 2006. But then they followed helpful directions of an assistant chemistry professor, added their own patience and ...
Research is shattering traditioinal notions of laser limits
Dec 07, 2009 |
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Air Force Office of Scientific Research and National Science Foundation-funded professor, Dr. Xiang Zhang has demonstrated at the University of California, Berkeley the world's smallest semiconductor laser, ...
HIV-related memory loss linked to Alzheimer's protein
Medicine & Health / Neuroscience
Dec 07, 2009 |
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More than half of HIV patients experience memory problems and other cognitive impairments as they age, and doctors know little about the underlying causes. New research from Washington University School of Medicine in St. ...
Green tea chemical combined with another may hold promise for treatment of brain disorders
Dec 03, 2009 |
4.8 / 5 (5) |
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Scientists at Boston Biomedical Research Institute (BBRI) and the University of Pennsylvania have found that combining two chemicals, one of which is the green tea component EGCG, can prevent and destroy a variety of protein ...
Study Unravels Detail of 'Most Important' Cellular Signal
Dec 03, 2009 |
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(PhysOrg.com) -- A new study provides crucial details that promise to help researchers better understand, and perhaps fine-tune with drugs, one of the most important signaling mechanisms in human cells, according to a study ...
Grooving down the helix: Researchers show how proteins slide along DNA to carry out vital biological processes
Dec 03, 2009 |
4 / 5 (3) |
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(PhysOrg.com) -- A team of scientists has made a major step in understanding how molecules locate the genetic information in DNA that is necessary to carry out important biological processes.
The hidden lives of proteins
Dec 02, 2009 |
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An important Brandeis study appearing in the December 3 issue of Nature raises the curtain on the hidden lives of proteins at the atomic level. The study reports that for the first time, researchers used x ...
Soy peptide lunasin has anti-cancer, anti-inflammatory properties
Dec 02, 2009 |
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Two new University of Illinois studies report that lunasin, a soy peptide often discarded in the waste streams of soy-processing plants, may have important health benefits that include fighting leukemia and blocking the inflammation ...
Combining nanotubes and antibodies for breast cancer 'search and destroy' missions
Dec 02, 2009 |
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cylinders of carbon about a nanometer in diameter -- have been highly touted for potential applications such as ultrastrong fibers, electrical wires in molecular devices, or hydrogen storage components for ...
Scientists show how ubiquitin chains are added to cell-cycle proteins
Dec 02, 2009 |
4.7 / 5 (3) |
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Researchers from the California Institute of Technology (Caltech) have been able to view in detail, and for the first time, the previously mysterious process by which long chains of a protein called ubiquitin ...
