J3-Endorphin

Endogenous oligopeptides that bind with parts of opioid receptors and act analogous to opioids were observed in the brain and other tissues. The first of these to be isolated and decoded were met- and leu-enkephaUn. j3-Endorphin, a peptide with quite a large molecular mass and with analogous action, was found produced in pituitary gland. 

In the 1970s, Hughes et al. were the first to show that two very different chemical structures have similar agonist properties (3). The opioid natural product, morphine (3), was found to resemble the N-terminal structure of the endogenous opioid peptides, enkephalins, (4a) and (4b), and j3-endorphin (5) (Fig. 15.2). The remarkable similarity between the morphine phenol system and the IV-terminal tyrosine residue in the peptide opioids implied that these units reacted with opioid receptors in a similar fashion to elicit comparable responses (4-6). 

Nicotine binds selectively to the nicotinic receptors that are present in the adrenal medulla, brain, autonomic ganglia, and neuromuscular junctions. It causes the release of several neurotransmitters and hormones such as acetylcholine, norepinephrine, dopamine, serotonin, arginine vasopressin, j3-endorphin, adrenocorticotropic hormone, and cortisol (187). This neuro-regulatory effect of nicotine is dose-dependent and occurs as plasma nicotine level rises when tobacco is smoked. The neurotransmitters released in the brain medi-... 

The separation of three peptides insulin chains A and B and j3-endorphin fragments 1-27 was achieved under physiological conditions by a temperature change (Kanazawa and Okano, 2011). TTie temperature rise increases hydrophobicity of temperature-responsive carriers and hence the retention time of the peptides provides better separation (Fig. 13.3). As peptides have... 

The classical mammalian opioid peptides are derived from three distinct precursor proteins (Fig. 7.10) (see Refs. 75,266 for reviews). Processing of the precursor proteins occurs at pairs of basic residues. jS-Endorphin is derived from proopiomelanocortin (POMC), along with ACTH, a-MSH, and j3-lipotropin (see Ref 267 for a review). The enkephalins are derived from proenkephalin A (see Ref 268 for a review). This protein contains four copies of Met-enkephalin flanked by pairs of basic resi-... 

DAMGO Morphine Methadone Fentanyl Dermorphin crop Levorphanol Etorphine Naloxone Naltrexone j3-funaltrexamine Enkephalin Endorphin... 

Figure 33 Cleavage of pro-opiomelanocortin (POMC) into endorphin and non-opioid peptides. POMC serves as a precursor (pro-) for the opiate peptide, -endorphin (-opio-) for a-, J3- and y-melanocyte-stimulating hormone (MSH, -melano-) for adrenocortkotrophic hormone (ACTH, -cort-) and for a- and /3- lipotropin (-in). Notice that the peptides are not located end-to-end, but that some of the smaller peptide sequences are embedded in larger sequences (e.g., a-lipotropin, P-MSH and P-endorphin are contained within P-lipotropin). Two other protein precursors contain enkephalins and dynorphins. Proenkephalin contains seven met-enkephalin sequences (Tyr-Gly-Gly-Phe-Met). Prodynorphin contains three leu-enkephalin sequences (Tyr-Gly-Gly-Phe-Leu) and the sequences for dynorphin A, Dynorphin B, a-neodynorphin and P-neoendorphin.

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