Opioid Peptides are short sequences of
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H
2NCHRCOOH, where R is an organic substituent...
s that mimic the effect of
opiateIn medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant, as well as many semisynthetic chemical derivatives of such alkaloids.-Overview:...
s in the
brainThe brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all...
. Opioid peptides may be produced by the body itself, for example
endorphinEndorphins are endogenous opioid polypeptide compounds. They are produced by the pituitary gland and the hypothalamus in vertebrates during strenuous exercise, excitement, pain and orgasm, and they resemble the opiates in their abilities to produce analgesia and a feeling of well-being. Endorphins...
s, or be absorbed from partially
digestedDigestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be absorbed, for instance, by a blood stream. Digestion is a form of catabolism.that means break down of macro food molecules to smaller one....
foodFood is any substance, usually composed of carbohydrates, fats, proteins and water, that can be eaten or drunk by an animal, including humans, for nutrition or pleasure. Items considered food may be sourced from plants, animals or other categories such as fungus or fermented products like alcohol...
(
casomorphinsCasomorphins are peptides, i.e., protein fragments, derived from the digestion of milk protein. The distinguishing characteristic of casomorphins is that they have an opioid effect....
, exorphins and
rubiscolinsThe rubiscolins are a group of opioid peptides which are formed during digestion of the ribulose bisphosphate carboxylase/oxygenase protein from spinach leaves. Rubiscolins mimic the effects of opiates and therefore influence the brain. These peptides have much in common with the better known...
). The effect of these peptides vary, but they all resemble opiates. The opioid food peptides have lengths of typically 4-8 amino acids. The body's own opioids are generally much longer.
Brain opioid peptide systems are known to play an important role in motivation, emotion,
attachment behaviourAttachment theory is a psychological, evolutionary and ethological theory concerning relationships between humans. The most important tenet of attachment theory is that a young child needs to develop a relationship with at least one primary caregiver for normal social and emotional development...
, the response to stress and pain, and the control of food intake.
The human
genomeIn modern molecular biology the genome refers to all of its hereditary information encoded in DNA .The genome includes both the genes and the non-coding sequences of the DNA. The term was adapted in 1920 by Hans Winkler, Professor of Botany at the University of Hamburg, Germany...
contains three
homologousIn evolutionary biology, homology refers to any similarity between characteristics of organisms that is due to their shared ancestry. The word homologous derives from the ancient Greek ομολογειν, 'to agree'. There are examples in different branches of biology...
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s that are known to
codeThe genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells. A more precise term for the concept might be "genetic cipher". The code defines a mapping between tri-nucleotide sequences, called codons, and amino acids...
for endogenous opioid peptides.
Opioid Peptides are short sequences of
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H
2NCHRCOOH, where R is an organic substituent...
s that mimic the effect of
opiateIn medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant, as well as many semisynthetic chemical derivatives of such alkaloids.-Overview:...
s in the
brainThe brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all...
. Opioid peptides may be produced by the body itself, for example
endorphinEndorphins are endogenous opioid polypeptide compounds. They are produced by the pituitary gland and the hypothalamus in vertebrates during strenuous exercise, excitement, pain and orgasm, and they resemble the opiates in their abilities to produce analgesia and a feeling of well-being. Endorphins...
s, or be absorbed from partially
digestedDigestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be absorbed, for instance, by a blood stream. Digestion is a form of catabolism.that means break down of macro food molecules to smaller one....
foodFood is any substance, usually composed of carbohydrates, fats, proteins and water, that can be eaten or drunk by an animal, including humans, for nutrition or pleasure. Items considered food may be sourced from plants, animals or other categories such as fungus or fermented products like alcohol...
(
casomorphinsCasomorphins are peptides, i.e., protein fragments, derived from the digestion of milk protein. The distinguishing characteristic of casomorphins is that they have an opioid effect....
, exorphins and
rubiscolinsThe rubiscolins are a group of opioid peptides which are formed during digestion of the ribulose bisphosphate carboxylase/oxygenase protein from spinach leaves. Rubiscolins mimic the effects of opiates and therefore influence the brain. These peptides have much in common with the better known...
). The effect of these peptides vary, but they all resemble opiates. The opioid food peptides have lengths of typically 4-8 amino acids. The body's own opioids are generally much longer.
Brain opioid peptide systems are known to play an important role in motivation, emotion,
attachment behaviourAttachment theory is a psychological, evolutionary and ethological theory concerning relationships between humans. The most important tenet of attachment theory is that a young child needs to develop a relationship with at least one primary caregiver for normal social and emotional development...
, the response to stress and pain, and the control of food intake.
Opioid peptides produced by the body
The human
genomeIn modern molecular biology the genome refers to all of its hereditary information encoded in DNA .The genome includes both the genes and the non-coding sequences of the DNA. The term was adapted in 1920 by Hans Winkler, Professor of Botany at the University of Hamburg, Germany...
contains three
homologousIn evolutionary biology, homology refers to any similarity between characteristics of organisms that is due to their shared ancestry. The word homologous derives from the ancient Greek ομολογειν, 'to agree'. There are examples in different branches of biology...
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s that are known to
codeThe genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells. A more precise term for the concept might be "genetic cipher". The code defines a mapping between tri-nucleotide sequences, called codons, and amino acids...
for endogenous opioid peptides. Each gene codes for a large
proteinA protein precursor, also called a pro-protein or pro-peptide, is an inactive protein that can be turned into an active form by posttranslational modification. The name of the precursor for a protein is often prefixed by pro...
that can be
processedA protease breaks down proteins. A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein...
to yield smaller
peptidePeptides are short polymers formed from the linking, in a defined order, of α-amino acids. The link between one amino acid residue and the next is called an amide bond or a peptide bond....
s that have
opiateIn medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant, as well as many semisynthetic chemical derivatives of such alkaloids.-Overview:...
-like activity.
- The nucleotide sequence of the human gene for proopiomelanocortin
Pro-opiomelanocortin is a precursor polypeptide with 241 amino acid residues.This gene encodes a polypeptide hormone precursor that undergoes extensive, tissue-specific, post-translational processing via cleavage by subtilisin-like enzymes known as prohormone convertases...
(POMC) was characterized in 1980. The POMC gene codes for endogenous opiates such as β-endorphinBeta-endorphin is an endogenous opioid peptide neurotransmitter found in the neurons of both the central and peripheral nervous system.Sequence:...
and gamma-endorphin. The peptides with opiate activityOpioid receptors are a group of G-protein coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin...
that are derived from proopiomelanocortin comprise the class of endogenous opioid peptides called "endorphins".
- The human gene for enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, or specifically endorphins, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin were revealed, one...
s was isolated and its sequence described in 1982.
- The human gene for dynorphin
Dynorphins are a class of opioid peptides that arise from the precursor protein prodynorphin. When prodynorphin is cleaved during processing by proprotein convertase 2 , multiple active peptides are released: dynorphin A, dynorphin B, and α/β-neo-endorphin...
s (originally called the "Enkephalin B" gene because of sequence similarity to the enkephalin gene) was isolated and its sequence described in 1983.
- Opiorphin
Opiorphin is an endogenous chemical compound first isolated from human saliva. Initial research with mice shows the compound has a painkilling effect greater than that of morphine. It works by stopping the normal breakdown of natural pain-killing opioids in the spine, called enkephalins...
, found in human saliva, is an enkephalinase inhibitor, i.e. it prevents the metabolism of enkephalins.
Opioid foodFood is any substance, usually composed of carbohydrates, fats, proteins and water, that can be eaten or drunk by an animal, including humans, for nutrition or pleasure. Items considered food may be sourced from plants, animals or other categories such as fungus or fermented products like alcohol...
peptides
- Casomorphin
Casomorphins are peptides, i.e., protein fragments, derived from the digestion of milk protein. The distinguishing characteristic of casomorphins is that they have an opioid effect....
(from milkMilk is an opaque white liquid produced by the mammary glands of mammals. It provides the primary source of nutrition for young mammals before they are able to digest other types of food. The early lactation milk is known as colostrum, and carries the mother's antibodies to the baby. It can reduce...
)
- Gluten exorphin (from gluten
Gluten is a composite of the proteins gliadin and glutenin. These exist, conjoined with starch, in the endosperms of some grass-related grains, notably wheat, rye, and barley. Gliadin and glutenin comprise about 80% of the protein contained in wheat seed. Being insoluble in water, they can be...
)
- Gliadorphin/gluteomorphin
Gliadorphin is an opioid peptide which is formed during digestion of the gliadin component of the gluten protein. It is usually broken down into amino acids by digestion enzymes. It has been hypothesized that children with autism have abnormal leakage from the gut of this compound, which then...
(from glutenGluten is a composite of the proteins gliadin and glutenin. These exist, conjoined with starch, in the endosperms of some grass-related grains, notably wheat, rye, and barley. Gliadin and glutenin comprise about 80% of the protein contained in wheat seed. Being insoluble in water, they can be...
)
- Rubiscolin
The rubiscolins are a group of opioid peptides which are formed during digestion of the ribulose bisphosphate carboxylase/oxygenase protein from spinach leaves. Rubiscolins mimic the effects of opiates and therefore influence the brain. These peptides have much in common with the better known...
(from spinachSpinach is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant , which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions...
)
Microbial opioid peptides
- Deltorphin I and II (fungal
A fungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants, animals and bacteria...
)
- Dermorphin (from an unknown microbe)