描述
Dynorphin A is an endogenous opioid peptide that produces non-opioid receptor-mediated neural excitation.Dynorphin induces calcium influx via voltage-sensitive calcium channels in sensory neurons by activating bradykinin receptors. This action of dynorphin at bradykinin receptors is distinct from the primary signaling pathway activated by bradykinin and underlies the hyperalgesia produced by pharmacological administration of dynorphin by the spinal route in rats and mice. Blockade of spinal B1 or B2 receptor also reverses persistent neuropathic pain but only when there is sustained elevation of endogenous spinal dynorphin, which is required for maintenance of neuropathic pain. These data reveal a mechanism for endogenous dynorphin to promote pain through its agonist action at bradykinin receptors and suggest new avenues for therapeutic intervention.
Dynorphin A is a form of 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 (PC2), multiple active peptides are released: dynorphin A, dynorphin B, and a/b-neo-endorphin. Depolarization of a neuron containing prodynorphin stimulates PC2 processing, which occurs within synaptic vesicles in the presynaptic terminal. Occasionally, prodynorphin is not fully processed, leading to the release of "big dynorphin."This 32-amino acid molecule consists of both dynorphin A and dynorphin B.Dynorphin A, dynorphin B, and big dynorphin all contain a high proportion of basic amino acid residues, in particular lysine and arginine (29.4%, 23.1%, and 31.2% basic residues, respectively), as well as many hydrophobic residues (41.2%, 30.8%, and 34.4% hydrophobic residues, respectively). Although dynorphins are found widely distributed in the CNS, they have the highest concentrations in the hypothalamus, medulla, pons, midbrain, and spinal cord. Dynorphins are stored in large (80-120 nm diameter) dense-core vesicles that are considerably larger than vesicles storing neurotransmitters. These large dense-core vesicles differ from small synaptic vesicles in that a more intense and prolonged stimulus is needed to cause the large vesicles to release their contents into the synaptic cleft. Dense-core vesicle storage is characteristic of opioid peptides storage.
The first clues to the functionality of dynorphins came from Goldstein et al. in their work with opioid peptides. The group discovered an endogenous opioid peptide in the porcine pituitary that proved difficult to isolate. By sequencing the first 13 amino acids of the peptide, they created a synthetic version of the peptide with a similar potency to the natural peptide. Goldstein et al. applied the synthetic peptide to the guinea ileum longitudinal muscle and found it to be an extraordinarily potent opioid peptide. The peptide was called dynorphin (from the Greek dynamis=power) to describe its potency.
Dynorphins exert their effects primarily through the κ-opioid receptor (KOR), a G-protein-coupled receptor. Two subtypes of KORs have been identified: K1 and K2. Although KOR is the primary receptor for all dynorphins, the peptides do have some affinity for the μ-opioid receptor (MOR), d-opioid receptor (DOR), N-methyl-D-aspartic acid (NMDA)-type glutamate receptor . Different dynorphins show different receptor selectivities and potencies at receptors. Big dynorphin and dynorphin A have the same selectivity for human KOR, but dynorphin A is more selective for KOR over MOR and DOR than is big dynorphin. Big dynorphin is more potent at KORs than is dynorphin A. Both big dynorphin and dynorphin A are more potent and more selective than dynorphin B (from wiki) [HMDB]
InChI标识符
InChI=1S/C69H115N23O13/c1-7-41(6)56(65(104)88-49(22-15-31-81-69(77)78)66(105)92-32-16-23-53(92)64(103)87-46(19-11-12-28-70)60(99)89-50(57(72)96)33-39(2)3)91-61(100)48(21-14-30-80-68(75)76)85-59(98)47(20-13-29-79-67(73)74)86-62(101)51(34-40(4)5)90-63(102)52(36-42-17-9-8-10-18-42)84-55(95)38-82-54(94)37-83-58(97)45(71)35-43-24-26-44(93)27-25-43/h8-10,17-18,24-27,39-41,45-53,56,93H,7,11-16,19-23,28-38,70-71H2,1-6H3,(H2,72,96)(H,82,94)(H,83,97)(H,84,95)(H,85,98)(H,86,101)(H,87,103)(H,88,104)(H,89,99)(H,90,102)(H,91,100)(H4,73,74,79)(H4,75,76,80)(H4,77,78,81)/p+1/t41?,45-,46+,47-,48-,49-,50+,51-,52-,53+,56+/m1/s1