Protein Molecule
A Protein Molecule is an polypeptide that is longer than ~50 amino acids.
- Context:
- It can (often) have a Protein Sequence, and a Protein Structure.
- It can be represented in a Protein Knowledge Base.
- It can be an Enzyme.
- It can be a Nano-Scale Machine.
- It can range from being a Named Protein to being an Unnamed Product.
- It can range from being a Biologically-Produced Protein (such as an organism protein gene product) to being a Synthetically-Produced Protein.
- …
- Example(s):
- a Hemoglobin.
- a Toxin Regulated Pilin Protein.
- a Metalloprotease Enzyme.
- a Gluten.
- …
- Counter-Example(s):
- a Shorter Polypeptide.
- a Nucleic Acid, Lipid.
- a Gene.
- a Human Product.
- See: Biomolecule, Macromolecule, Enzyme Catalysis, DNA Replication, Cell Signaling, Nucleotide Sequence, Protein Folding.
References
2022
- (Wikipedia, 2022) ⇒ https://en.wikipedia.org/wiki/Peptide Retrieved:2022-6-5.
- … A polypeptide that contains more than approximately fifty amino acids is known as a protein. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, or to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. ...
2019
- https://deepmind.com/blog/alphafold/
- QUOTE: ... Proteins are large, complex molecules essential in sustaining life. Nearly every function our body performs — contracting muscles, sensing light, or turning food into energy—can be traced back to one or more proteins and how they move and change. The recipes for those proteins — called genes — are encoded in our DNA.
What any given protein can do depends on its unique 3D structure. For example, antibody proteins that make up our immune systems are ‘Y-shaped’, and are akin to unique hooks. By latching on to viruses and bacteria, antibody proteins are able to detect and tag disease-causing microorganisms for extermination. Similarly, collagen proteins are shaped like cords, which transmit tension between cartilage, ligaments, bones, and skin. Other types of proteins include CRISPR and Cas9, which act like scissors and cut and paste DNA; antifreeze proteins, whose 3D structure allows them to bind to ice crystals and prevent organisms from freezing; and ribosomes that act like a programmed assembly line, which help build proteins themselves.
But figuring out the 3D shape of a protein purely from its genetic sequence is a complex task that scientists have found challenging for decades. The challenge is that DNA only contains information about the sequence of a protein’s building blocks called amino acid residues, which form long chains. Predicting how those chains will fold into the intricate 3D structure of a protein is what’s known as the “protein folding problem”.
The bigger the protein, the more complicated and difficult it is to model because there are more interactions between amino acids to take into account. As noted in Levinthal’s paradox, it would take longer than the age of the universe to enumerate all the possible configurations of a typical protein before reaching the right 3D structure. ...
- QUOTE: ... Proteins are large, complex molecules essential in sustaining life. Nearly every function our body performs — contracting muscles, sensing light, or turning food into energy—can be traced back to one or more proteins and how they move and change. The recipes for those proteins — called genes — are encoded in our DNA.
2014
- (Wikipedia, 2014) ⇒ http://en.wikipedia.org/wiki/protein Retrieved:2014-3-1.
- Proteins ( /ˈproʊˌtiːnz/ or ) are large biological molecules, or macromolecules, consisting of one or more chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in folding of the protein into a specific three-dimensional structure that determines its activity.
A polypeptide is a single [[linear
- Proteins ( /ˈproʊˌtiːnz/ or ) are large biological molecules, or macromolecules, consisting of one or more chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, replicating DNA, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in folding of the protein into a specific three-dimensional structure that determines its activity.
polymer]] chain derived from the condensation of amino acids. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues 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 posttranslational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors. Proteins can also work together to achieve a particular function, and they often associate to form stable protein 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 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, nuclear magnetic resonance and mass spectrometry.
2009
- MeSH:D.12.776
- "Polymers of amino acids linked by peptide bonds. The specific sequence of amino acids determines the shape and function of the protein."