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

An improved method for protein crystal structure visualization

X-ray crystal structure visualization technique has been known for over a hundred years. While it keeps improving, it is extremely difficult to focus rays on objects that are invisible to the naked eye, such as proteins. ...

Method triggers selective degradation of proteins for analysis

Scientists of Ludwig-Maximilians-Universitaet (LMU) in Munich have developed a tool to eliminate essential proteins from cells with a flash of light. The new method makes it possible to study the function of essential proteins.

Taming electrons with bacteria parts

Electrons are tough to pin down in biology. Learning how to harness electrons is no fool's errand because, when electrons move, they are the electricity that powers life.

Researchers solve protein structures to fight asthma

Biophysicists from the MIPT Center for Molecular Mechanisms of Aging and Age-Related Diseases have teamed up with colleagues from Canada, the U.S., Japan, France, and Germany to shed light on the structure and functioning ...

Surveying all the proteins on a neuron's surface

Scientists have found a new way to home in on the proteins covering a particular cell's surface. The feat offers insight into how brain cells form intricate networks during development.

Factors that ensure cellular protein production

Defects in tRNA biogenesis influence gene expression and are associated with many types of human diseases, such as cancer and neurological diseases. In his thesis, Fu Xu contributes to new knowledge about the factors that ...

Scientists create decoy molecule that neutralizes arenaviruses

A host of disease-causing viruses called arenaviruses lurk in animal populations in various parts of the world, sometimes crossing over into humans. When they do cross over, they can be lethal, and only very few treatments ...

New mechanisms describe how the genome regulates itself

An organism's genome contains all of the information necessary for each of its cells and tissues to develop and function properly. Written in DNA, each individual gene encodes for something, whether it is a structural protein ...

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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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