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
Green tea chemical combined with another may hold promise for treatment of brain disorders
Dec 03, 2009 |
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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 ...
Scientists show how ubiquitin chains are added to cell-cycle proteins
Dec 02, 2009 |
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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 ...
Vitamin E extract could help tackle cancer tumours
Dec 03, 2009 |
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(PhysOrg.com) -- An extract of vitamin E could have a key role to play in the treatment of cancerous tumours, according to newly-published research today.
Grooving down the helix: Researchers show how proteins slide along DNA to carry out vital biological processes
Dec 03, 2009 |
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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 ...
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 ...
It takes two to infect: Structural biologists shed light on mechanism of invasion protein
Nov 30, 2009 |
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Bacteria are quite creative when infecting the human organism. They invade cells, migrate through the body, avoid an immune response and misuse processes of the host cell for their own purposes. To this end every bacterium ...
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 ...
ERK's got rhythm: Protein that controls cell growth found to cycle in and out of cell nucleus (w/ Video)
Dec 01, 2009 |
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Time-lapsed video of individual breast tissue cells reveals a never-before-seen event in the life of a cell: a protein that cycles between two major compartments in the cell. The results give researchers a more complete view ...
Can cleft palate be healed before birth?
Dec 01, 2009 |
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In a study newly published in the journal Development, investigators at the USC School of Dentistry describe how to non-surgically reverse the onset of cleft palate in fetal mice - potentially one step in the journey to a b ...
High urea levels in chronic kidney failure might be toxic after all
Dec 02, 2009 |
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It is thought that the elevated levels of urea (the byproduct of protein breakdown that is excreted in the urine) in patients with end-stage kidney failure are not particularly toxic.
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 ...
New therapy targets for amyloid disease
Dec 04, 2009 |
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A major discovery is challenging accepted thinking about amyloids - the fibrous protein deposits associated with diseases such as Alzheimer's and Parkinson's - and may open up a potential new area for therapeutics.
