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
Scientists discover how the brain encodes memories at a cellular level
Dec 23, 2009 |
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Scientists at UC Santa Barbara have made a major discovery in how the brain encodes memories. The finding, published in the December 24 issue of the journal Neuron, could eventually lead to the development ...
Study shows a key protein helps control blood pressure
Dec 23, 2009 |
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University of Iowa researchers have shown that a protein channel helps nerve sensors in blood vessels keep blood pressure in check. Without the protein channel, known as ASIC2, the sensors are unable to send the brain the ...
Subtle change dramatically reduces pathogenic potential of Huntington's protein
Dec 23, 2009 |
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Scientists have identified a key molecular switch that may drive the onset of Huntington's disease (HD), an incurable neurodegenerative disorder that leads to severe disruptions in muscle coordination and cognitive function. ...
Synergistic interaction enhances pathogenesis of Parkinson's disease
Dec 23, 2009 |
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Scientists have identified a synergistic interaction that disrupts normal intracellular transport mechanisms and leads to the accumulation of neuron-damaging clumps of protein associated with Parkinson's disease (PD), a neurodegenerative ...
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Critical protein helps mend damaged DNA
5 hours ago |
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In order to preserve our DNA, cells have developed an intricate system for monitoring and repairing DNA damage. Yet precisely how the initial damage signal is converted into a repair response remains unclear. Researchers ...
Scientists identify protein that keeps stem cells poised for action
5 hours ago |
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Like a child awaiting the arrival of Christmas, embryonic stem cells exist in a state of permanent anticipation. They must balance the ability to quickly become more specialized cell types with the cellular chaos that could ...
First adhere, then detach and glide forward
Dec 23, 2009 |
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How do one-celled parasites move from the salivary gland of a mosquito through a person's skin into red blood cells? What molecular mechanisms form the basis for this very important movement of the protozoa? ...
Research yields new agent for some drug-resistant non-small cell lung cancers
Dec 23, 2009 |
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The ability to make, test, and map the atomic structure of new anti-cancer agents has enabled a team of Dana-Farber Cancer Institute scientists to discover a compound capable of halting a common type of drug-resistant ...
A novel gene found for childhood-onset asthma
Dec 23, 2009 |
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Pediatric researchers have identified a novel gene involved in childhood asthma, in one of the largest gene studies to date of the common respiratory disease. Because the gene, called DENND1B, affects cells and signaling ...
Knockdown of E2F1 reduces invasive potential of melanoma cells
Dec 23, 2009 |
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Inhibition of transcription factor E2F1 reduced epidermal growth factor receptor (EGFR) expression and reduced the invasive potential but not proliferation of metastatic melanoma cells, according to a brief communication ...
Molecular anchor links the 2 inheritable diseases Fanconi anemia and Bloom's syndrome
5 hours ago |
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A new study establishes a molecular link that bridges two rare inherited disorders and explains why these diseases result in genetic instability. The research, published by Cell Press in the December 24th issue of the journal ...
New insights into mushroom-derived drug promising for cancer treatment
Dec 23, 2009 |
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A promising cancer drug, first discovered in a mushroom commonly used in Chinese medicine, could be made more effective thanks to researchers who have discovered how the drug works. The research is funded by the Biotechnology ...
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