protein

[ proh-teen, -tee-in ]

noun

1. Biochemistry. any of numerous, highly varied organic molecules constituting a large portion of the mass of every life form and necessary in the diet of all animals and other nonphotosynthesizing organisms, composed of 20 or more amino acids linked in a genetically controlled linear sequence into one or more long polypeptide chains, the final shape and other properties of each protein being determined by the side chains of the amino acids and their chemical attachments: proteins include such specialized forms as collagen for supportive tissue, hemoglobin for transport, antibodies for immune defense, and enzymes for metabolism.
2. the plant or animal tissue rich in such molecules, considered as a food source supplying essential amino acids to the body.
3. (formerly) a substance thought to be the essential nitrogenous component of all organic bodies.

adjective

1. Biochemistry. of the nature of or containing protein.

protein

/ ˈprəʊtiːn /

noun

1. any of a large group of nitrogenous compounds of high molecular weight that are essential constituents of all living organisms. They consist of one or more chains of amino acids linked by peptide bonds and are folded into a specific three-dimensional shape maintained by further chemical bonding

protein

/ prō′tēn′ /

1. Any of a large class of complex organic chemical compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures, usually containing alpha helices and beta sheets as well as looping and folded chains. Enzymes, antibodies, and hemoglobin are examples of proteins.

Derived Forms

• ˌproteinˈaceous, adjective

Other Words From

• pro·tein·a·ceous [proh-tee-, ney, -sh, uh, s, -tee-i-, ney, -], pro·teinic pro·teinous adjective
• non·protein noun

Word History and Origins

Origin of protein¹

First recorded in 1835–45; from German Protein, from Greek prōte(îos) “primary” + German -in -in ²; replacing proteine, from French; proto- ( def )

Word History and Origins

Origin of protein¹

C19: via German from Greek prōteios primary, from protos first + -in

A Closer Look

Proteins are the true workhorses of the body, carrying out most of the chemical processes and making up the majority of cellular structures. Proteins are made up of long chains of amino acids, but they don't resemble linear pieces of spaghetti. The atoms in these long chains have their own attractive and repulsive properties. Some of the amino acids can form bonds with other molecules in the chain, kinking and twisting and folding into complicated, three-dimensional shapes, such as helixes or densely furrowed globular structures. These folded shapes are immensely important because they define the protein's function in the cell. Some protein shapes fit perfectly in cell receptors, turning chemical processes on and off, like a key in a lock, whereas others work to transport molecules throughout the body (hemoglobin's shape is ideal for carrying oxygen). When proteins fail to take on their preordained shapes, there can be serious consequences: misfolded proteins have been implicated in diseases such as Alzheimer's, mad cow, and Parkinson's, among others. Exactly how proteins are able to fold into their required shapes is poorly understood and remains a fundamental question in biochemistry.

Example Sentences

Because these proteins were gathered from CSF, they are a good proxy for activity in the brain, and several of them may be potential targets for therapies.

From Science Daily

Genes contain the essential building instructions for life, guiding cells on which amino acids to assemble in what sequence to produce specific proteins.

From Science Daily

However, in specific contexts, these proteins can be misused and shield cancer cells from death.

From Science Daily

According to the scientist, "This functions like a dial, in which higher activity of the protein translates to less intense red colour."

From Science Daily

Researchers have identified new roles for a protein long known to protect against severe flu infection -- among them, raising the minimum number of viral particles needed to cause sickness.

From Science Daily