Related topics: cells · genes · cancer · cancer cells · amino acids

New sensor detects rare metals used in smartphones

A more efficient and cost-effective way to detect lanthanides, the rare earth metals used in smartphones and other technologies, could be possible with a new protein-based sensor that changes its fluorescence when it binds ...

DNA managed like climbing rope to avoid knots

A process that cells use to unravel knotted strands of DNA – resembling a method used to control climbing ropes – has been uncovered by scientists.

Taming the genome's 'jumping' sequences

The human genome is fascinating. Once predicted to contain about a hundred thousand protein-coding genes, it now seems that the number is closer to twenty thousand, and maybe less. And although our genome is made up of about ...

Multiple modes for selectivity of transmembrane transport

LMU researchers utilized a biophysical approach to understand how bacterial import proteins bind and selectively convey their cargoes across membranes. The results reveal an unexpectedly wide variety of transfer mechanisms.

Cell-killing proteins suppress listeria without killing cells

New North Carolina State University research shows that key proteins known for their ability to prevent viral infections by inducing cell death can also block certain bacterial infections without triggering the death of the ...

Turning an old enemy into a helpful friend

Half our genome is basically foreign, derived from viruses. Obviously, the invasion of such foreign elements can deregulate critical biological processes, and lead to disease. This is why animals, including humans have evolved ...

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Protein

Proteins (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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