0-Endorphin model peptides

Taylor, Kaiser, and their co-workers (Taylor and Kaiser, 1986) prepared a series of model peptides that were designed to test the role of each of the postulated modules in /8-endorphin. Figure 13 illustrates a-helical net diagrams of the proposed helical auxiliary sequence of /3-endorphin. The hydrophobic residues in this structure cover half the surface of the helix, twisting around the structure in a clockwise manner. [It has also been noted that if this sequence were to form a tt helix rather than an a... 

Dynorphin may also influence nociception at the spinal level. The levels of prodynorphin mRNA and immunoreactive dynorphin increase in the chronic inflammatory arthritic model (158). Dynorphin also inhibits morphine or P-endorphin-induced analgesia in naive animals and enhances analgesia in tolerant animals, indicating that this peptide may have a regulatory role in opioid analgesia (159). This effect does not appear to be mediated by a classical opioid receptor, since des-tyrosine dynorphin, which does not bind to opioid receptors, also antagonizes morphine analgesia (160). 

The aforementioned synthetic modeling approach, which was so successfully applied to studying the structural properties of /3-endorphin, appears to be general and has been applied to the study of several other peptide hormones and hormone-releasing factors including glucagon... 

Opioid peptides have also been tested in animal models of depression and of antidepressant activity. Enkephalins and endorphins decreased immobility in the forced swim test and in the learned helplessness paradigm, demonstrating... 

Since the discovery and characterization of P-endorphin (31 amino acids) as an opioid peptide in 1976, the opinion has been widely held that this peptide has a role in the control of pain (Akil et al., 1984 Basbaum and Fields, 1984 Loh et al 1976 Rossier et al., 1977). POMC-derived P-endorphin is considered to be a key component of the endogenous antinociceptive system attenuating the stress- and inflammation-induced hyperalgesia (Rossier et al., 1977 Stein et al., 1990 Sun et al., 2003). It binds with high affinity to both MOR and DOR (Akil et al., 1984). Pain stimulation induces PAG release of 3-endorphin and the ICV administration of 3-endorphin produces analgesia (Akil et al., 1984). Similarly, both spinal and peripheral administration of 3-endorphin evokes antinociceptive effects in different pain models (Chung et al., 1994 Stein et al., 1990 Suh et al., 1994 Suh et al.,... 

Kumagai AK, Eisenberg JB, Pardiidge WM (1987) Absorptive-mediated endocytosis of cationized albumin and a beta-endorphin-cationized albumin chimeric peptide by isolated brain capillaries. Model system of blood-brain barrier transport. J Biol Chem 262 15214—15219. 

The work flow for dPLIMSTEX starts with half the volume of an equilibrated protein-peptide complex for measurement. The other half is diluted in aqueous buffer before incubation (Figure 11.5). The dilution step is continued until the concentration of the peptide is too low to be detected. dPLIMSTEX was first demonstrated by using a model system, calcium-saturated calmodulin with the opioid peptide )-endorphin it yielded a similar binding constant as that determined by standard PLIMSTEX and other methods. dPLIMSTEX was then applied to a monoclonal antinitro-tyrosine antibody, in complex with a 3-nitrotyrosine-modified peptide system. A binding stoichiometry of 1 2 was confirmed. In addition, a in the low nM range and a minimum of five amino... 

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