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

Designing biological movement on the nanometer scale

Synthetic proteins have been created that move in response to their environment in predictable and tunable ways. These motile molecules were designed from scratch on computers, then produced inside living cells.

What artificial intelligence can teach us about proteins

Proteins are vital parts of all living organisms and perform essential tasks in our bodies. They build and repair tissues, supply components of the immune and hormone systems, regulate metabolism, and transmit signals. Researchers ...

Study uncovers key step in cell protein production

Scientists at the University of Sheffield have discovered how genes create proteins in research which could aid the development of treatments for human diseases.

A 'biomultimeter' to measure RNA and protein production in real-time

Builders of genetic circuits face the same quandary as builders of digital circuits: testing their designs. Yet unlike bioengineers, engineers have a simple and universal testing tool—the multimeter—that they can touch ...

Key acid-activated protein channel identified

Johns Hopkins researchers have discovered a long-sought protein, the proton-activated chloride channel (PAC), that is activated in acidic environments and could protect against the tissue-damaging effects of stroke, heart ...

Extreme cold could reveal herpesvirus infection dynamics

The funny thing about the virus that causes chicken pox is that no one knows for sure how it or many of its herpesvirus cousins invade and infect cells. It's a bit of a problem: Without that knowledge, it's been hard to find ...

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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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