Oligomer
Encyclopedia
In chemistry
, an oligomer is a molecule that consists of a few monomer
units (ολιγος, or oligos, is Greek for "a few"), in contrast to a polymer
that, at least in principle, consists of an unlimited number of monomers. Dimers, trimer
s, and tetramer
s are oligomers. Many oils are oligomeric, such as liquid paraffin
. Plasticizers are oligomeric ester
s widely used to soften thermoplastics such as PVC
. They may be made from monomer
s by linking them together, or by separation from the higher fractions of crude oil. Polybutene
is an oligomeric oil used to make putty
. Greek prefixes are often used to designate the number of monomer units in the oligomer, for example a tetramer being composed of four units and a hexamer of six.
In biochemistry
, the term oligomer is used for short, single-stranded nucleic acid
fragments, such as DNA or RNA, or similar fragments of analogs of nucleic acids such as peptide nucleic acid or Morpholino
s. Such oligos are used in hybridization experiments (bound to glass slides or nylon
membranes), as probes for in situ hybridization
or in antisense experiments such as gene knockdown
s. It can also refer to a protein complex
made of two or more subunit
s. In this case, a complex made of several different protein
subunits is called a hetero-oligomer or heteromer
. When only one type of protein
subunit is used in the complex, it is called a homo-oligomer or homomer.
Oligomerization is a chemical process that converts monomers to a finite degree of polymerization
. The actual figure is a matter of debate, often a value between 10 and 100.
When an oligomer forms as a result of chain transfer
the oligomer is called a telomer and the process telomerization
. A telomere
is a region of highly repetitive DNA at the end of a linear chromosome.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, an oligomer is a molecule that consists of a few monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
units (ολιγος, or oligos, is Greek for "a few"), in contrast to a polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
that, at least in principle, consists of an unlimited number of monomers. Dimers, trimer
Trimer (chemistry)
In chemistry, a trimer is a product derived from three identical precursors. Trimers are typically cyclic. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids. Often, trimerization competes with polymerization....
s, and tetramer
Tetramer
A tetramer is a protein with four subunits . There are homotetramers such as glutathione S-transferase or single-strand binding protein, dimers of hetero-dimers such as hemoglobin , and heterotetramers, where each subunit is different.-Subunit interactions in tetramers:The interactions between...
s are oligomers. Many oils are oligomeric, such as liquid paraffin
Liquid paraffin (medicinal)
Medicinal liquid paraffin is a very highly refined mineral white oil used in cosmetics and for medical purposes. This is a UK definition and the term may have different uses in other countries...
. Plasticizers are oligomeric ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s widely used to soften thermoplastics such as PVC
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
. They may be made from monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
s by linking them together, or by separation from the higher fractions of crude oil. Polybutene
Polybutene
Polybutene and polyisobutylene are liquid oligomers widely used as plasticizers for high-molecular weight polymers, such as polyethylene. They are not to be confused with the high molecular weight polymer polybutene-1.-Properties:...
is an oligomeric oil used to make putty
Putty
Putty is a generic term for a plastic material similar in texture to clay or dough typically used in domestic construction and repair as a sealant or filler. Painter's Putty is typically a linseed oil based product used for filling holes, minor cracks and defacements in wood only...
. Greek prefixes are often used to designate the number of monomer units in the oligomer, for example a tetramer being composed of four units and a hexamer of six.
In biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
, the term oligomer is used for short, single-stranded nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
fragments, such as DNA or RNA, or similar fragments of analogs of nucleic acids such as peptide nucleic acid or Morpholino
Morpholino
In molecular biology, a Morpholino is a molecule in a particular structural family that is used to modify gene expression. Morpholino oligomers are an antisense technology used to block access of other molecules to specific sequences within nucleic acid...
s. Such oligos are used in hybridization experiments (bound to glass slides or nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
membranes), as probes for in situ hybridization
In situ hybridization
In situ hybridization is a type of hybridization that uses a labeled complementary DNA or RNA strand to localize a specific DNA or RNA sequence in a portion or section of tissue , or, if the tissue is small enough , in the entire tissue...
or in antisense experiments such as gene knockdown
Gene knockdown
Gene knockdown refers to techniques by which the expression of one or more of an organism's genes is reduced, either through genetic modification or by treatment with a reagent such as a short DNA or RNA oligonucleotide with a sequence complementary to either an mRNA transcript or a gene...
s. It can also refer to a protein complex
Protein complex
A multiprotein complex is a group of two or more associated polypeptide chains. If the different polypeptide chains contain different protein domain, the resulting multiprotein complex can have multiple catalytic functions...
made of two or more subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
s. In this case, a complex made of several different protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
subunits is called a hetero-oligomer or heteromer
Heteromer
-Pharmacology:* Ligand-gated ion channels such as the nicotinic acetylcholine receptor and GABAA receptor are composed of five subunits arranged around a central pore that opens to allow ions to pass through. There are a large number of different subunits available, which can come together in a...
. When only one type of protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
subunit is used in the complex, it is called a homo-oligomer or homomer.
Oligomerization is a chemical process that converts monomers to a finite degree of polymerization
Degree of polymerization
The degree of polymerization, or DP, is usually defined as the number of monomeric units in a macromolecule or polymer or oligomer molecule.For a homopolymer, there is only one type of monomeric unit andthe number-average degree of polymerization is given by...
. The actual figure is a matter of debate, often a value between 10 and 100.
When an oligomer forms as a result of chain transfer
Chain transfer
Chain transfer is a polymerization reaction by which the activity of a growing polymer chain is transferred to another molecule.Chain transfer reactions reduce the average molecular weight of the final polymer...
the oligomer is called a telomer and the process telomerization
Telomerization
Telomerization is a radical polymerization reaction where a chain transfer limits the size of the oligomer molecule product—the telomer. Telomerization requires a telogen to react with at least one unsaturated taxogen molecule. Fluorotelomers are an example.-See also:*Perfluorooctanoic acid...
. A telomere
Telomere
A telomere is a region of repetitive DNA sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Its name is derived from the Greek nouns telos "end" and merοs "part"...
is a region of highly repetitive DNA at the end of a linear chromosome.
See also
- OligoesterOligoesterAn oligoester is an ester oligomer chain containing a small number of repeating ester units . Oligoesters are short analogs of polymeric polyesters.An example is oligo--3-hydroxybutyrate....
- OligopeptideOligopeptideAn oligopeptide consists of between 2 and 20 amino acids and includes dipeptides, tripeptides, tetrapeptides, pentapeptides, etc.Examples of oligopeptides include:...
- Paraffin wax
- Protein quaternary structure
- PolybutenePolybutenePolybutene and polyisobutylene are liquid oligomers widely used as plasticizers for high-molecular weight polymers, such as polyethylene. They are not to be confused with the high molecular weight polymer polybutene-1.-Properties:...