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A new dimension for 3-D protein structures

(Phys.org) —3D structures of biological molecules like proteins directly affect the way they behave in our bodies. EPFL scientists have developed a new infrared-UV laser method to more accurately determine ...

Chemistry - Biochemistry

May 13, 2013

5 / 5 (4)

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A silky spin on protective armor

At seven times the toughness of Kevlar, a silk produced by the Caerostris darwini spider of Madagascar is more robust than any other material—synthetic or natural. Most spider silks are about two times ...

Chemistry - Materials Science

May 13, 2013

5 / 5 (4)

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Flower power fights orchard pests

Washington State University researchers have found they can control one of fruit growers' more severe pests, aphids, with a remarkably benign tool: flowers. The discovery is a boon for organic as well as ...

Biology - Ecology

May 14, 2013

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Water governs cell movement

Water gives life. Researchers at Linköping University in Sweden now show how the cells in our bodies are driven mainly by water power – a discovery that in the long run opens the way for a new strategy ...

Biology - Cell & Microbiology

May 14, 2013

5 / 5 (1)

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Novel probe for live human iPS cell imaging

Researchers from the National Institute of Advanced Industrial Science and Technology (AIST) have developed a highly sensitive lectin probe, rBC2LCN, for human induced pluripotent stem cells (iPS cells). ...

Biology - Cell & Microbiology

May 16, 2013

5 / 5 (1)

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Receptor proteins could hold clues to antibiotic resistance in MRSA

Scientists at Imperial College London have identified four new proteins that act as receptors for an essential signalling molecule in bacteria such as MRSA.

Biology - Cell & Microbiology

May 13, 2013

4 / 5 (1)

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Combining chromatography, proteomics and database searching identifies hard-to-find heme proteins

(Phys.org) —Iron is a critical part of many biological processes; however, it is often not biologically available or it can be toxic in high quantities. So, biological systems have developed intricate methods ...

Biology - Cell & Microbiology

May 14, 2013

4 / 5 (1)

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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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