Medications

A 'smashing' solution for cancer therapy

Sometimes too much of a good thing is not good at all. Inhibiting the function of the PD-1 protein, which blocks immune function, has shown high therapeutic efficacy in cancer immunotherapy. However, when this function is ...

Cardiology

Removing protein makes non-stick arteries

Stray platelets from our blood can stick to the linings of our blood vessels, eventually causing clogs, heart attacks and strokes. But platelets make poor targets for heart disease drugs; making platelets less prone to clogs ...

Medical research

Circadian clocks play a key role in fat cell growth

Disruption of the circadian clocks that keep the body and its cells entrained to the 24-hour day-night cycle plays a critical role in weight gain, according to a pair of studies by Weill Cornell Medicine investigators.

Alzheimer's disease & dementia

Novel way to diagnose Alzheimer's disease by blood analysis

Using proteomics and other advanced tools of molecular biology, an international team of researchers led by a group from Karolinska Institutet have found a novel way to diagnose Alzheimer's disease by blood analysis, with ...

Health

On nutrition: Questions about incomplete proteins

Reader Ann F. writes: "I remember learning a bit about incomplete proteins a long time ago, and that if you combined, say, beans with corn, you had a complete protein, much as if you'd eaten eggs, or meat, or cottage cheese. ...

Cardiology

Study finds two protein pathways downregulated in postnatal heart

In work published today in Stem Cell Reports, researchers from the University of Minnesota Medical School discovered two signaling pathways that are downregulated in human hearts after birth. These pathways, mitogen-activated ...

Diseases, Conditions, Syndromes

Bacteria-busting proteins offer potential for smarter drugs

A specific group of bacteria-killing proteins inside the immune system could hold the key to developing smarter and more effective drugs capable of eliminating certain infectious diseases including meningitis, pneumonia and ...

page 1 from 40

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.

This text uses material from Wikipedia, licensed under CC BY-SA