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Peptides (, ) are short chains of
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
s linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called
oligopeptide An oligopeptide, often just called peptide ('' oligo-'', "a few"), consists of two to twenty amino acids and can include dipeptides, tripeptides, tetrapeptides, and pentapeptides. Some of the major classes of naturally occurring oligopeptides in ...
s, and include
dipeptide A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiologicall ...
s,
tripeptide A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the constituent amino acids and their sequence. The simplest tripeptide is glycine ...
s, and
tetrapeptide A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors in p ...
s. A polypeptide is a longer, continuous, unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids,
oligosaccharide An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple sug ...
s, polysaccharides, and others. A polypeptide that contains more than approximately 50 amino acids is known as a
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to
ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...
s such as
coenzyme A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that ass ...
s and cofactors, or to another protein or other macromolecule such as DNA or RNA, or to complex
macromolecular assemblies The term macromolecular assembly (MA) refers to massive chemical structures such as viruses and non-biologic nanoparticles, cellular organelles and membranes and ribosomes, etc. that are complex mixtures of polypeptide, polynucleotide, polys ...
. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each
amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it i ...
bond.. All peptides except
cyclic peptide Cyclic peptides are polypeptide chains which contain a circular sequence of bonds. This can be through a connection between the amino and carboxyl ends of the peptide, for example in cyclosporin; a connection between the amino end and a side chai ...
s have an N-terminal (amine group) and
C-terminal The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...
(carboxyl group) residue at the end of the peptide (as shown for the tetrapeptide in the image).


Classes

There are numerous types of peptides that have been classified according to their sources and functions. According to the Handbook of Biologically Active Peptides, some groups of peptides include plant peptides, bacterial/ antibiotic peptides, fungal peptides, invertebrate peptides, amphibian/skin peptides, venom peptides, cancer/anticancer peptides, vaccine peptides, immune/inflammatory peptides, brain peptides, endocrine peptides, ingestive peptides, gastrointestinal peptides, cardiovascular peptides, renal peptides, respiratory peptides,
opiate peptide An opiate, in classical pharmacology, is a substance derived from opium. In more modern usage, the term ''opioid'' is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain (including antagonist ...
s,
neurotrophic Neurotrophic factors (NTFs) are a family of biomolecules – nearly all of which are peptides or small proteins – that support the growth, survival, and differentiation of both developing and mature neurons. Most NTFs exert their tro ...
peptides, and blood–brain peptides. Some ribosomal peptides are subject to proteolysis. These function, typically in higher organisms, as
hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...
s and signaling molecules. Some microbes produce peptides as antibiotics, such as
microcin Microcins are very small bacteriocins, composed of relatively few amino acids. For this reason, they are distinct from their larger protein cousins. The classic example is microcin V, of ''Escherichia coli''. Subtilosin A is another bacterioci ...
s and
bacteriocin Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ec ...
s. Peptides frequently have
post-translational modification Post-translational modification (PTM) is the covalent and generally enzymatic modification of proteins following protein biosynthesis. This process occurs in the endoplasmic reticulum and the golgi apparatus. Proteins are synthesized by ribos ...
s such as phosphorylation, hydroxylation,
sulfonation Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution. Aryl sulfonic acids are used as detergents, dye, and drugs. Stoichiometry a ...
,
palmitoylation Palmitoylation is the covalent attachment of fatty acids, such as palmitic acid, to cysteine (''S''-palmitoylation) and less frequently to serine and threonine (''O''-palmitoylation) residues of proteins, which are typically membrane protein ...
, glycosylation, and
disulfide In biochemistry, a disulfide (or disulphide in British English) refers to a functional group with the structure . The linkage is also called an SS-bond or sometimes a disulfide bridge and is usually derived by the coupling of two thiol groups. In ...
formation. In general, peptides are linear, although
lariat A lasso ( or ), also called lariat, riata, or reata (all from Castilian, la reata 're-tied rope'), is a loop of rope designed as a restraint to be thrown around a target and tightened when pulled. It is a well-known tool of the Spanish an ...
structures have been observed. More exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in
platypus venom The platypus is one of the few living mammals to produce venom. The venom is made in venom glands that are connected to hollow spurs on their hind legs; it is primarily made during the mating season. While the venom's effects are described as e ...
. ''
Nonribosomal peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacter ...
s'' are assembled by
enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s, not the ribosome. A common non-ribosomal peptide is
glutathione Glutathione (GSH, ) is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, pe ...
, a component of the antioxidant defenses of most aerobic organisms. Other nonribosomal peptides are most common in
unicellular organism A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms a ...
s,
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
s, and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
and are synthesized by
modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
enzyme complexes called ''nonribosomal peptide synthetases''. These complexes are often laid out in a similar fashion, and they can contain many different modules to perform a diverse set of chemical manipulations on the developing product. These peptides are often
cyclic Cycle, cycles, or cyclic may refer to: Anthropology and social sciences * Cyclic history, a theory of history * Cyclical theory, a theory of American political history associated with Arthur Schlesinger, Sr. * Social cycle, various cycles in s ...
and can have highly complex cyclic structures, although linear nonribosomal peptides are also common. Since the system is closely related to the machinery for building
fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...
s and
polyketide Polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone (or reduced forms of a ketone) and methylene groups: (-CO-CH2-). First studied in the early 20th century, discovery, biosynth ...
s, hybrid compounds are often found. The presence of
oxazoles Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak ...
or
thiazoles Thiazole, or 1,3-thiazole, is a heterocyclic compound that contains both sulfur and nitrogen. The term 'thiazole' also refers to a large family of derivatives. Thiazole itself is a pale yellow liquid with a pyridine-like odor and the molecular fo ...
often indicates that the compound was synthesized in this fashion. ' are derived from animal milk or meat digested by proteolysis. In addition to containing small peptides, the resulting material includes fats, metals, salts, vitamins, and many other biological compounds. Peptones are used in nutrient media for growing bacteria and fungi. ''Peptide fragments'' refer to fragments of proteins that are used to identify or quantify the source protein. Often these are the products of enzymatic degradation performed in the laboratory on a controlled sample, but can also be forensic or paleontological samples that have been degraded by natural effects.


Chemical synthesis


Example families

The peptide families in this section are ribosomal peptides, usually with hormonal activity. All of these peptides are synthesized by cells as longer "propeptides" or "proproteins" and truncated prior to exiting the cell. They are released into the bloodstream where they perform their signaling functions.


Antimicrobial peptides

*
Magainin The magainins are a class of antimicrobial peptides found in the African clawed frog (''Xenopus laevis''). The peptides are cationic, generally lack a stable conformation in water but form amphipathic α-helix in membranes; their mechanism agains ...
family *
Cecropin Cecropins are antimicrobial peptides. They were first isolated from the hemolymph of ''Hyalophora cecropia'', whence the term cecropin was derived. Cecropins lyse bacterial cell membranes; they also inhibit proline uptake and cause leaky membrane ...
family *
Cathelicidin Cathelicidin antimicrobial peptide (CAMP) is a polypeptide that is primarily stored in the lysosomes of macrophages and polymorphonuclear leukocytes (PMNs); in humans, the ''CAMP'' gene encodes the peptide precursor CAP-18 (18 kDa), which is proce ...
family * Defensin family


Tachykinin peptides

*
Substance P Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its clo ...
* Kassinin *
Neurokinin A Neurokinin A (NKA), formerly known as Substance K, is a neurologically active peptide translated from the pre-protachykinin gene. Neurokinin A has many excitatory effects on mammalian nervous systems and is also influential on the mammalian inflam ...
*
Eledoisin Eledoisin is an undecapeptide of mollusk origin, belonging to the tachykinin family of neuropeptides. It was first isolated from the posterior salivary glands of two mollusk species ''Eledone muschata'' and ''Eledone aldovandi'', which belong to ...
*
Neurokinin B Neurokinin B (NKB) belongs in the family of tachykinin peptides. Neurokinin B is implicated in a variety of human functions and pathways such as the secretion of gonadotropin-releasing hormone. Additionally, NKB is associated with pregnancy in fem ...


Vasoactive intestinal peptides

*
VIP A very important person or personage (VIP or V.I.P.) is a person who is accorded special privileges due to their high social status, influence or importance. The term was not common until sometime after World War 2 by RAF pilots. Examples inc ...
(''Vasoactive Intestinal Peptide''; PHM27) *
PACAP Pituitary adenylate cyclase-activating polypeptide also known as PACAP is a protein that in humans is encoded by the ''ADCYAP1'' gene. pituitary adenylate cyclase-activating polypeptide is similar to vasoactive intestinal peptide. One of its effect ...
''Pituitary Adenylate Cyclase Activating Peptide'' *
Peptide PHI Peptide PHI, also known as peptide histidine isoleucine, is a peptide which functions as a hormone. This peptide contains a composition of 27 amino acids with histidine on the N-terminus and isoleucine on the C-terminus. It was originally isolated f ...
27 (''Peptide Histidine Isoleucine 27'') * GHRH 1-24 ''(Growth Hormone Releasing Hormone 1-24)'' * Glucagon * Secretin


Pancreatic polypeptide-related peptides

* NPY ''(NeuroPeptide Y) * PYY ''(Peptide YY)'' * APP ''(Avian Pancreatic Polypeptide)'' * PPY ''Pancreatic PolYpeptide''


Opioid peptides

*
Proopiomelanocortin Pro-opiomelanocortin (POMC) is a precursor polypeptide with 241 amino acid residues. POMC is synthesized in corticotrophs of the anterior pituitary from the 267-amino-acid-long polypeptide precursor pre-pro-opiomelanocortin (pre-POMC), by the ...
(POMC) peptides *
Enkephalin An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephali ...
pentapeptides *
Prodynorphin Prodynorphin, also known as proenkephalin B, is an opioid polypeptide hormone involved with chemical signal transduction and cell communication. The gene for prodynorphin is expressed in the endometrium and the striatum, and its gene map locus is 20 ...
peptides


Calcitonin peptides

*
Calcitonin Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing th ...
*
Amylin Amylin, or islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone. It is co-secreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1 (insulin:amylin). Amylin plays a role in glycemic regulation by sl ...
*
AGG01 AGG01 a peptide antibiotic discovered in the breast milk of the Tammar wallaby, reportedly one hundred times more powerful than penicillin ''in vitro''. This compound was found to be effective against MRSA, '' E. coli'', ''Streptococci'', ''Salm ...


Self-assembling peptides

* Aromatic short peptides * Biomimetic peptides * Peptide amphiphiles *Peptide dendrimers


Other peptides

* B-type Natriuretic Peptide (BNP) - produced in the myocardium and useful in medical diagnosis *
Lactotripeptides Lactotripeptides are two naturally occurring milk peptides: Isoleucine-Proline-Proline (IPP) and Valine-Proline-Proline (VPP). These lactotripeptides are derived from casein, which is a milk protein also found in dairy products. Although most norma ...
- Lactotripeptides might reduce blood pressure, although the evidence is mixed. * Peptidic components from traditional Chinese medicine Colla Corii Asini in hematopoiesis.


Terminology


Length

Several terms related to peptides have no strict length definitions, and there is often overlap in their usage: * A ''polypeptide'' is a single linear chain of many amino acids (any length), held together by amide bonds. * A ''
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
'' consists of one or more polypeptides (more than about 50 amino acids long). * An ''
oligopeptide An oligopeptide, often just called peptide ('' oligo-'', "a few"), consists of two to twenty amino acids and can include dipeptides, tripeptides, tetrapeptides, and pentapeptides. Some of the major classes of naturally occurring oligopeptides in ...
'' consists of only a few amino acids (between two and twenty).


Number of amino acids

Peptides and proteins are often described by the number of amino acids in their chain, e.g. a protein with 158 amino acids may be described as a "158 amino-acid-long protein". Peptides of specific shorter lengths are named using
IUPAC numerical multiplier The numerical multiplier (or multiplying affix) in IUPAC nomenclature indicates how many particular atoms or functional groups are attached at a particular point in a molecule. The affixes are derived from both Latin and Greek. Compound aff ...
prefixes: * A ''
monopeptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called Protein, proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapepti ...
'' has one amino acid. * A ''
dipeptide A dipeptide is an organic compound derived from two amino acids. The constituent amino acids can be the same or different. When different, two isomers of the dipeptide are possible, depending on the sequence. Several dipeptides are physiologicall ...
'' has two amino acids. * A ''
tripeptide A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the constituent amino acids and their sequence. The simplest tripeptide is glycine ...
'' has three amino acids. * A ''
tetrapeptide A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors in p ...
'' has four amino acids. * A ''pentapeptide'' has five amino acids. (''e.g.'',
enkephalin An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephali ...
). * A ''hexapeptide'' has six amino acids. (''e.g.'', angiotensin IV). * A ''heptapeptide'' has seven amino acids. (''e.g.'', spinorphin). * An ''octapeptide'' has eight amino acids (''e.g.'', angiotensin II). * A ''nonapeptide'' has nine amino acids (''e.g.'', oxytocin). * A ''decapeptide'' has ten amino acids (''e.g.'',
gonadotropin-releasing hormone Gonadotropin-releasing hormone (GnRH) is a releasing hormone responsible for the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior pituitary. GnRH is a tropic peptide hormone synthesized and release ...
and
angiotensin I Angiotensin is a peptide hormone that causes vasoconstriction and an increase in blood pressure. It is part of the renin–angiotensin system, which regulates blood pressure. Angiotensin also stimulates the release of aldosterone from the a ...
). * A ''undecapeptide'' has eleven amino acids (''e.g.'',
substance P Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) and a member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its clo ...
). The same words are also used to describe a group of residues in a larger polypeptide (''e.g.'',
RGD motif Arginylglycylaspartic acid (RGD) is the most common peptide motif responsible for cell adhesion to the extracellular matrix (ECM), found in species ranging from ''Drosophila'' to humans. Cell adhesion proteins called integrins recognize and bind ...
).


Function

* A ''
neuropeptide Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the ...
'' is a peptide that is active in association with neural tissue. * A ''
lipopeptide A lipopeptide is a molecule consisting of a lipid connected to a peptide. They are able to self-assemble into different structures. Many bacteria produced these molecules as a part of their metabolism, especially those of the genus ''Bacillus'', ' ...
'' is a peptide that has a
lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...
connected to it, and ''
pepducin Pepducins are cell-penetrating peptides that act as intracellular modulators of signal transference from receptors to G proteins. Pepducins were first developed at the Tufts Medical Center laboratories of Dr. Athan Kuliopulos and Dr. Lidija Covic ...
s'' are lipopeptides that interact with GPCRs. * A ''
peptide hormone Peptide hormones or protein hormones are hormones whose molecules are peptide, or proteins, respectively. The latter have longer amino acid chain lengths than the former. These hormones have an effect on the endocrine system of animals, including h ...
'' is a peptide that acts as a
hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...
. * A proteose is a mixture of peptides produced by the hydrolysis of proteins. The term is somewhat archaic. * A peptidergic agent (or drug) is a chemical which functions to directly modulate the peptide systems in the body or brain. An example is
opioidergic An opioidergic agent (or drug) is a chemical which functions to directly modulate the opioid neuropeptide systems (i.e., endorphin, enkephalin, dynorphin, nociceptin) in the body or brain. Examples include opioid analgesics such as morphine a ...
s, which are neuropeptidergics. * A cell-penetrating peptide is a peptide able to penetrate the cell membrane.


See also

* Acetyl hexapeptide-3 * Beefy meaty peptide * Collagen hybridizing peptide, a short peptide that can bind to denatured collagen in tissues * Bis-peptide *
CLE peptide CLE peptides (CLAVATA3/Embryo Surrounding Region-Related) are a group of peptides found in plants that are involved with cell signaling. Production is controlled by the CLE genes. Upon binding to a CLE peptide receptor in another cell, a chain react ...
* Epidermal growth factor * ''
Journal of Peptide Science The ''Journal of Peptide Science'' is a monthly peer-reviewed scientific journal, published since 1995 by John Wiley & Sons on behalf of the European Peptide Society. The current editor-in-chief is Paolo Rovero ( Universita di Firenze). Abstract ...
'' *
Lactotripeptides Lactotripeptides are two naturally occurring milk peptides: Isoleucine-Proline-Proline (IPP) and Valine-Proline-Proline (VPP). These lactotripeptides are derived from casein, which is a milk protein also found in dairy products. Although most norma ...
*
Micropeptide Micropeptides (also referred to as microproteins) are polypeptides with a length of less than 100-150 amino acids that are encoded by short open reading frames (sORFs). In this respect, they differ from many other active small polypeptides, which ...
*
Multifunctional peptide A multifunctional peptide is a peptide which occurs when two genes band together. This process gives new properties to the polypeptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called ...
*
Neuropeptide Neuropeptides are chemical messengers made up of small chains of amino acids that are synthesized and released by neurons. Neuropeptides typically bind to G protein-coupled receptors (GPCRs) to modulate neural activity and other tissues like the ...
*
Palmitoyl pentapeptide-4 Palmitoyl pentapeptide-4 (palmitoyl pentapeptide-3 before 2006) is a matrikine used in anti-wrinkle cosmetics. It was launched in 2000 as an active ingredient for the personal care industry under the trade name Matrixyl by the French cosmetic act ...
* Pancreatic hormone * peptide spectral library *
Peptide synthesis In organic chemistry, peptide synthesis is the production of peptides, compounds where multiple amino acids are linked via amide bonds, also known as peptide bonds. Peptides are chemically synthesized by the condensation reaction of the carboxyl ...
*
Peptidomimetic A peptidomimetic is a small protein-like chain designed to mimic a peptide. They typically arise either from modification of an existing peptide, or by designing similar systems that mimic peptides, such as peptoids and β-peptides. Irrespective ...
s (such as
peptoid Peptoids (root from the Greek language, Greek πεπτός, ''peptós'' "digested"; derived from πέσσειν, ''péssein'' "to digest" and the Greek-derived suffix -oid meaning "like, like that of, thing like a ______," ), or poly-''N''-substit ...
s and β-peptides) to peptides, but with different properties. *
Protein tag Protein tags are peptide sequences genetically grafted onto a recombinant protein. Tags are attached to proteins for various purposes. They can be added to either end of the target protein, so they are either C-terminus or N-terminus specific or a ...
, describing addition of peptide sequences to enable protein isolation or detection *
Replikins Replikins are a group of peptides, whose increase in concentration in virus or other organism proteins is associated with rapid replication. It is often measured in number of replikins per 100 amino acids. This particular group of peptides have bee ...
* Ribosome *
Translation (biology) In molecular biology and genetics, translation is the process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesize proteins after the process of transcription of DNA to RNA in the cell's nucleus. The entire proces ...


References

{{Authority control Peptides