Spinorphin
Encyclopedia
Spinorphin is an endogenous
, non-classical opioid peptide
of the hemorphin
family, which was first isolated from the bovine spinal cord
(hence the prefix spin-) and acts as a regulator of the enkephalinase
s, a class of enzyme
s which break down endogenous the enkephalin
peptide
s. It does so by inhibiting the enzyme
s aminopeptidase N (APN), dipeptidyl peptidase III (DPP3), angiotensin-converting enzyme
(ACE), and neutral endopeptidase (NEP). Spinorphin is a heptapeptide and has the amino acid sequence Leu-Val-Val-Tyr-Pro-Trp-Thr (LVVYPWT). It has been observed to possess antinociceptive, antiallodynic, and anti-inflammatory
properties. The mechanism of action
of spinorphin has not been fully elucidated (i.e., how it acts to inhibit the enkephalinases), but it has been found to act as an antagonist
of the P2X3 receptor
, and as a weak partial agonist
/antagonist of the FP1 receptor
.
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...
, non-classical opioid peptide
Opioid peptide
Opioid peptides are short sequences of amino acids that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Opioid peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but they all resemble opiates...
of the hemorphin
Hemorphin
Hemorphins are a class of naturally-occurring, endogenous opioid peptides which are found in the bloodstream, and are derived from the beta-chain of hemoglobin...
family, which was first isolated from the bovine spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
(hence the prefix spin-) and acts as a regulator of the enkephalinase
Enkephalinase
Enkephalinases are enzymes which degrade endogenous enkephalin opioid peptides. They include:* Aminopeptidase N * Neutral endopeptidase * Dipeptidyl peptidase 3 * Carboxypeptidase A6 * Angiotensin-converting enzyme...
s, a class of enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s which break down endogenous the enkephalin
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...
peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
s. It does so by inhibiting the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s aminopeptidase N (APN), dipeptidyl peptidase III (DPP3), angiotensin-converting enzyme
Angiotensin-converting enzyme
Angiotensin I-converting enzyme , an exopeptidase, is a circulating enzyme that participates in the body's renin-angiotensin system , which mediates extracellular volume , and arterial vasoconstriction...
(ACE), and neutral endopeptidase (NEP). Spinorphin is a heptapeptide and has the amino acid sequence Leu-Val-Val-Tyr-Pro-Trp-Thr (LVVYPWT). It has been observed to possess antinociceptive, antiallodynic, and anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....
properties. The mechanism of action
Mechanism of action
In pharmacology, the term mechanism of action refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect...
of spinorphin has not been fully elucidated (i.e., how it acts to inhibit the enkephalinases), but it has been found to act as an antagonist
Receptor antagonist
A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...
of the P2X3 receptor
P2RX3
P2X purinoceptor 3 is a protein that in humans is encoded by the P2RX3 gene....
, and as a weak partial agonist
Partial agonist
Partial agonists bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist...
/antagonist of the FP1 receptor
Formyl peptide receptor 1
fMet-Leu-Phe receptor also known as the N-formyl peptide receptor is a protein that in humans is encoded by the FPR1 gene.-Further reading:...
.