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 |
4.7 / 5 (10) |
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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 ...
Computational microscope peers into the working ribosome (w/ Video)
Nov 23, 2009 |
4.9 / 5 (9) |
2
Two new studies reveal in unprecedented detail how the ribosome interacts with other molecules to assemble new proteins and guide them toward their destination in biological cells. The studies used molecular ...
Ice Cold: Cooler Than Being Cool
Nov 24, 2009 |
4.2 / 5 (10) |
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(PhysOrg.com) -- Water expands when it freezes. Anyone who has ever left a can of soda or bottle of water in the freezer too long has witnessed this first hand. So how do plants and animals survive severe ...
Vibrations key to efficiency of green fluorescent protein
Nov 11, 2009 |
4.5 / 5 (6) |
1
University of California, Berkeley, chemists have discovered the secret to the success of a jellyfish protein whose green glow has made it the darling of biologists and the subject of the 2008 Nobel Prize ...
New findings bring hope for possible Parkinson's disease cure
Nov 03, 2009 |
5 / 5 (4) |
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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.
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 ...
Small nanoparticles bring big improvement to medical imaging
Nanotechnology / Bio & Medicine
Nov 18, 2009 |
5 / 5 (3) |
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If you're watching the complex processes in a living cell, it is easy to miss something important—especially if you are watching changes that take a long time to unfold and require high-spatial-resolution ...
Study sheds light on brain's fear processing center
Nov 25, 2009 |
5 / 5 (3) |
1
Breathing carbon dioxide can trigger panic attacks, but the biological reason for this effect has not been understood. A new study by University of Iowa researchers shows that carbon dioxide increases brain acidity, which ...
Atomic-level Snapshot Catches Protein Motor in Action (w/ Video)
Nov 20, 2009 |
4.7 / 5 (3) |
1
(PhysOrg.com) -- The atomic-level action of a remarkable class of ring-shaped protein motors has been uncovered by researchers with the Lawrence Berkeley National Laboratory using a state-of-the-art protein ...
Magnetic Nanotags Spot Cancer in Mice Earlier Than Current Methods
Nanotechnology / Bio & Medicine
Nov 17, 2009 |
3 / 5 (2) |
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(PhysOrg.com) -- Searching for biomarkers that can warn of diseases such as cancer while they are still in their earliest stage is likely to become far easier thanks to an innovative biosensor chip developed by Stanford University ...
Golden Oldie: Key Role for Ancient Protein in Algae Photosynthesis
Nov 27, 2009 |
3 / 5 (2) |
2
The discovery that an ancient light harvesting protein plays a pivotal role in the photosynthesis of green algae should help the effort to develop algae as a biofuels feedstock. Researchers with the Lawrence ...
NIST quantifies low levels of 'heart attack risk' protein
Chemistry / Analytical Chemistry
Nov 04, 2009 |
5 / 5 (1) |
0
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 reveal a new mechanism that increases atherosclerosis in mice
Nov 05, 2009 |
5 / 5 (1) |
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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, ...
Drought resistance explained
Nov 09, 2009 |
5 / 5 (1) |
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Much as adrenaline coursing through our veins drives our body's reactions to stress, the plant hormone abscisic acid (ABA) is behind plants' responses to stressful situations such as drought, but how it does ...
Amyloid beta protein gets bum rap
Nov 09, 2009 |
5 / 5 (1) |
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While too much amyloid beta protein in the brain is linked to the development of Alzheimer's disease, not enough of the protein in healthy brains can cause learning problems and forgetfulness, Saint Louis University scientists ...
