protein
Americannoun
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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.
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the plant or animal tissue rich in such molecules, considered as a food source supplying essential amino acids to the body.
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(formerly) a substance thought to be the essential nitrogenous component of all organic bodies.
adjective
noun
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.
Other Word Forms
- nonprotein noun
- proteinaceous adjective
- proteinic adjective
- proteinous adjective
Etymology
Origin of protein
First recorded in 1835–45; from German Protein, from Greek prōte(îos) “primary” + German -in -in 2; replacing proteine, from French; proto- ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
These reactive oxygen species damage cells through oxidation, stripping electrons from essential components such as lipids, proteins, and DNA.
From Science Daily
Because the imaging was label free, the samples were not treated with dyes, fluorescent proteins or molecular tags.
From Science Daily
Peptides are short chains of amino acids, or small proteins, which our bodies naturally produce.
From BBC
First, they analyzed data from 133 protein coding genes alongside fossil information to build a revised evolutionary timeline.
From Science Daily
In many organisms, cells divide by building a ring made of the protein actin at the cell's midpoint.
From Science Daily
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
