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

X-ray laser sight reveals drug targets

Researchers from the Moscow Institute of Physics and Technology have published a review on serial femtosecond crystallography, one of the most promising methods for analyzing the tertiary structure of proteins. This technique ...

From bugs to drugs

A new study led by Prof Shoumo Bhattacharya has decoded the structure of unique proteins found in tick saliva and created new ones not found in nature, paving the way for a new generation of "Swiss-army knife' anti-inflammatory ...

The ABC of ribosome recycling

Ribosomes, the essential machinery used for protein synthesis is recycled after each one round of translation. An enzyme called ABCE1 is responsible for this process and turns out to be remarkably plastic as LMU biophysicists ...

'Semi-synthetic' bacteria churn out unnatural proteins

Synthetic biologists seek to create new life with forms and functions not seen in nature. Although scientists are a long way from making a completely artificial life form, they have made semi-synthetic organisms that have ...

New function for the nucleolus

The nucleolus is a well-known structure in the cell nucleus that is easily visible under a light microscope. This nuclear structure is known to be the site of ribosome production. A new study shows that the nucleolus is also ...

Study gives insight into sun-induced DNA damage and cell repair

A team led by a Baylor University researcher has published a breakthrough article that provides a better understanding of the dynamic process by which sunlight-induced DNA damage is recognized by the molecular repair machinery ...

Preventing colorectal cancer and stillbirths

Characterizing a tiny protein—determining its shape and what it does—was the first step taken by Dr. Kirsten Wolthers and her colleagues in their effort to learn more about a very common molecule that is implicated in ...

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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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