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

An evolution in the understanding of evolution

Remember domain, kingdom, phylum, class, order, family, genus, species and Charles Darwin's "tree of life" metaphor we learned about in high school biology? That way of describing living-things lineages is just science's ...

A new approach to reconstructing protein evolution

There are an estimated 20,000 to 30,000 proteins at work in cells, where they carry out numerable functions, says computational molecular biologist Roman Sloutsky at the University of Massachusetts Amherst. "One of the central ...

How roots grow hair

The roots of plants can do a lot of things: They grow in length to reach water, they can bend to circumvent stones, and they form fine root hairs enabling them to absorb more nutrients from the soil. A team of researchers ...

Structural protein essential for ciliary harmony in comb jellies

Researchers from the University of Tsukuba's Shimoda Marine Research Center and the Japanese National Institute for Basic Biology have identified a protein that keeps millions of tiny surface organelles moving in harmony ...

Aҫaí berry extracts fight malaria in mice

Despite humanity's best efforts to eradicate malaria, the disease struck more than 200 million people in 2017, according to the World Health Organization. Worse yet, the parasite that causes malaria is developing resistance ...

Tackling E. coli infections

Monash scientists have identified a survival mechanism of bacteria that cause disease in plant and animals, including highly virulent E. coli (Escherichia coli) related diseases.

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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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