Health

Put down the protein shake: Variety of protein better for health

Amino acids have long been touted by the fitness and bodybuilding communities for their muscle building benefits. From ultra-bulk protein powders to lean mass-promoting snack bars, there's no shortage of products available ...

Parkinson's & Movement disorders

New research shows Parkinson's disease origins in the gut

In experiments in mice, Johns Hopkins Medicine researchers say they have found additional evidence that Parkinson's disease originates among cells in the gut and travels up the body's neurons to the brain. The study, described ...

Alzheimer's disease & dementia

Alzheimer's disease is a 'double-prion disorder,' study shows

Two proteins central to the pathology of Alzheimer's disease act as prions—misshapen proteins that spread through tissue like an infection by forcing normal proteins to adopt the same misfolded shape—according to new ...

Cardiology

Red and white meats are equally bad for cholesterol

Contrary to popular belief, consuming red meat and white meat such as poultry, have equal effects on blood cholesterol levels, according to a study published today in the American Journal of Clinical Nutrition.

Diabetes

Researchers identify trigger and mechanism in type 1 diabetes

Researchers at National Jewish Health have identified an elusive trigger of type 1 diabetes. A protein fragment formed in the pancreas activates the immune system's T cells, leading them to attack and destroy beta cells, ...

Health

Quorn protein builds muscle better than milk protein

A study from the University of Exeter has found that mycoprotein, the protein-rich food source that is unique to Quorn products, stimulates post-exercise muscle building to a greater extent than milk protein.

Alzheimer's disease & dementia

Scientists propose new theory on Alzheimer's, amyloid connection

Worldwide, 50 million people are living with Alzheimer's disease and other dementias. According to the Alzheimer's Association, every 65 seconds someone in the United States develops this disease, which causes problems with ...

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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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