Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peptides can be adsorbed on octadecasilyl-silica from large volumes of aqueous solution and eluted with aqueous solvent mixtures containing methanol or acetonitrile. These properties may be used for the extraction and purification of peptide fragments in plasma samples collected from rats. After intravenous injection of Synacthen [corticotropin-(1-24)-tetracosapeptide], it was shown that within 2 min the main circulating products were intact peptide and its sulphoxide. In addition, a number of fragments indicative of cleavage at the N- and C-termini were present. Most of the products formed from Synacthen have low biological activity. Somatostatin was rapidly cleaved in vivo and in vitro to a single product, which probably retains biological activity. The absence of other circulating products suggests that somatostatin is only inactivated once it leaves the circulation.
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PMID:Use of octadecasilyl-silica for the extraction and purification of peptides in biological samples. Application to the identification of circulating metabolites of corticotropin-(1-24)-tetracosapeptide and somatostatin in vivo. 20 57

Circular dichroic spectra of camel beta-endorphin and ovine beta-lipotropin in water show little, if any, secondary structure. Intrinsic viscosities and sedimentation coefficients of the two peptides also suggest that the molecules are not compact and globular. Methanol or sodium dodecyl sulfate promotes the formation of helical structure to an extent as much as one-half of either peptide molecule. The conformation of the complex between camel beta-endorphin and dodecyl sulfate may be related to the opiate-like function of this peptide hormone.
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PMID:Conformation of beta-endorphin and beta-lipotropin: formation of helical structure in methanol and sodium dodecyl sulfate solutions. 26 86

The release of leu- and met-enkephalin from rat striatal slices was determined by superfusing the slices in vitro and running the superfusates directly over columns of Amberlite XAD-2 from which the peptides were eluted with methanol and measured by radioimmunoassay. Depolarization by high K concentrations increased the release of both pentapeptides many fold; the degree of increase, however, depended in part on the length of time chosen for the stimulation period, suggesting that the stimulation effect was very short lived. The stimulated release of both peptides (but not the resting release) was at least partially dependent on Ca in the medium and was totally inhibited by high Mg concentrations. Selected concentrations of naloxone and morphine in the superfusing medium had no effect on the resting or stimulated release of the peptides. The results support the hypothesis that these peptides serve as neurotransmitters in the striatum, but autoregulation of their release by morphine and naloxone could not be demonstrated.
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PMID:K-stimulated release of leu- and met-enkephalin from rat striatal slices: lack of effect of morphine and naloxone. 46 1

1 A method is described for the rapid extraction of opioid peptides from the brain and other tissues. The method is based on acid extraction of tissues followed by adsorption of the extract onto Amberlite XAD-2 resin. Elution with methanol separates the enkephalins and alpha-endorphin from beta-endorphin.2 Over 90% of the opioid peptide activity isolated from brain and gut of several species by our method was due to methionine- and leucine-enkephalin. In contrast, the major opioid peptide activity recovered from the pituitary was due to peptides of much greater mol. wt. than the enkephalins.3 An opioid peptide with properties unlike those of the known endorphins or enkephalins was present in brain extracts. This peptide, termed epsilon-endorphin, has an apparent mol. wt. of 700 to 1200; it constituted between 5 to 10% of the total opioid activity in our extracts.4 A differential assay of methionine- and leucine-enkephalin was made either by destroying methionine-enkephalin activity with cyanogen bromide or by separating the peptides by thin layer chromatography.5 The ratio of methionine-enkephalin to leucine-enkephalin varied greatly in different brain regions. The highest proportions of leucine-enkephalin were found in the cerebral cortex and hippocampus.6 Formaldehyde perfusion and fixation of the brain in vivo had no significant effect on the brain content of enkephalin, indicating that proteolytic breakdown is not a major problem in the extraction of these peptides.7 It is suggested that the enkephalins may have a neurotransmitter role in both brain and peripheral tissues and that methionine- and leucine-enkephalin may subserve separate neuronal functions.
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PMID:The distribution of methionine-enkephalin and leucine-enkephalin in the brain and peripheral tissues. 59 68

A specific double antibody radioimmunoassay (RIA) for human-Corticotropin-Releasing Hormone (hCRF) using an antibody to synthetic hCRF was established. This antibody allowed a usable range of 10 pg to 5 ng of CRF per ml in the assay. Comparing the efficiency of various plasma extraction procedures, the extraction with ice-cold methanol was found to be the most simple and rapid method with an extraction efficiency of more than 80%. The reliability of the radioimmunoassay was shown under physiological and pathophysiological conditions.
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PMID:Radioimmunoassay of corticotropin-releasing hormone. 209 59

The developmental toxicology of 13 industrial alcohols (methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, tertiary-butanol, 1-pentanol, 1-hexanol, 2-ethyl-1-hexanol, 1-octanol, 1-nonanol, and 1-decanol), and the behavioral teratogenicity of 4 of these alcohols, were assessed in a series of experiments. The results of individual alcohols have been published previously, but the present paper summarizes the results in view of structure-activity relationships among these alcohols. The alcohols were administered by inhalation for 7 hours per day (6 hours/day for 1-decanol) on gestation days 1-19 to groups of approximately 15 pregnant Sprague-Dawley rats. For developmental toxicology evaluations, dams were sacrificed on gestation day 20. Fetuses were serially removed, weighed, sexed, and examined for external malformations. The frequency of visceral malformations and variations was determined in one-half of the fetuses, and the frequency of skeletal deviations was determined in the other half. Behavioral teratology endpoints were investigated in groups of 15 pregnant rats exposed to one of four alcohols (ethanol, 1-propanol, 1-butanol, and tertiary-butanol) and also involved groups of 18 male rats which were exposed to the same concentrations of each alcohol for 6 weeks, and then mated to untreated females. In the behavioral teratology evaluations, all litters were culled to eight pups and fostered to unexposed mothers. Offspring were tested from days 10-90 on a series of behavioral tests designed to evaluate neuromotor integrity, activity levels, learning, and memory. Additionally, brains were removed from 10 offspring per group at 21 days of age, and were dissected into cerebrum, cerebellum, brainstem, and midbrain; these samples were assayed for steady-state levels of protein and the neurotransmitters acetylcholine, dopamine, norepinephrine, 5-hydroxytryptamine (serotonin), substance P, B-endorphin, and met-enkephalin. Congenital malformations were noted for methanol, 1-propanol, isopropanol, and 1-butanol, but only at concentrations in excess of 5000 ppm. These concentrations also produced toxicity in the maternal animals; thus, there was little evidence of selective developmental toxicity among the alcohols. Although sporadic behavioral and neurochemical deviations were detected, no consistent pattern of effects was seen for any of the alcohols we tested. It should be noted that alcohols with chain lengths longer than the butyl series could not be generated as vapors at sufficiently high concentrations to produce observable toxicity in the maternal animals. This limits the generality of these findings to the possible developmental effects of these alcohols when taken through other routes of exposure.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Developmental toxicology of industrial alcohols: a summary of 13 alcohols administered by inhalation to rats. 223 24

Effects of opioid peptides (beta-endorphin, dynorphin (1-13). alpha-neoendorphin, beta-neoendorphin, leucine-enkephalin, methionine-enkephalin) on the release of thyrotropin-releasing hormone (TRH) from the rat caecum were studied in vitro. The rat caecum was incubated in medium 199 with 1.0 mg/ml of bacitracin (pH 7.4) (medium). The amount of TRH release from the rat caecum into the medium was measured by radioimmunoassay. The immunoreactive TRH (ir-TRH) release from the rat caecum was inhibited significantly in a dose-related manner with the addition of opioid peptides. The inhibitory effects of opioid peptides on ir-TRH release from the rat caecum were blocked with an addition of naloxone. The elution profile of acid-methanol-extracts of rat caecum on Sephadex G-10 was identical to that of synthetic TRH. The findings suggest that opioid peptides inhibit TRH release from the rat caecum in vitro.
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PMID:Effects of opioid peptides on thyrotropin-releasing hormone release from the rat caecum in vitro. 250 16

An 'antisense' peptide ('HTCA'), whose sequence was generated by reading the antisense RNA sequence corresponding to ACTH (1-24) was shown to bind ACTH (1-24) with a Kd of 0.3 nM in a solid-matrix binding assay [( 1986) Biochem. J. 234, 679 683]. Two-dimensional NMR spectra were used to examine the conformational behavior in methanol and in water solution of two fragments of adrenocorticotropin, ACTH(1-24) and ACTH (1-13), as well as their antisense peptides, HTCA and HTCA(12-24). The conformations are extended chains in these solutions, both as isolated molecules and when mixed with their antisense complements. The Kd values are greater than 1 mM.
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PMID:Conformational behavior of fragments of adrenocorticotropin and their antisense peptides determined by NMR spectroscopy and CD spectropolarimetry. 254 6

Protein methylesterase (PME) amino acid composition and substrate specificity towards methylated normal and deamidated protein substrates were investigated. The enzyme contained 23% acidic and 5% basic residues. These values are consistent with a pI of 4.45. The product formed from methylated protein by PME was confirmed as methanol by h.p.l.c. The kcat. and Km values for several methylated protein substrates ranged from 20 x 10(-6) to 560 x 10(-6) s-1 and from 0.5 to 64 microM respectively. However, the kcat./Km ratios ranged within one order of magnitude from 11 to 52 M-1.s-1. Results with the irreversible cysteine-proteinase inhibitor E-64 suggested that these low values were in part due to the fact that only one out of 25 molecules in the PME preparations was enzymically active. When PME was incubated with methylated normal and deamidated calmodulin, the enzyme hydrolysed the latter substrate at a higher rate. The Km and kcat. for methylated normal calmodulin were 0.9 microM and 31 x 10(-6) s-1, whereas for methylated deamidated calmodulin values of 1.6 microM and 188 x 10(-6) s-1 were obtained. The kcat./Km ratios for methylated normal and deamidated calmodulin were 34 and 118 M-1.s-1 respectively. By contrast, results with methylated adrenocorticotropic hormone (ACTH) substrates indicated that the main difference between native and deamidated substrates resides in the Km rather than the kcat. The Km for methylated deamidated ACTH was 5-fold lower than that for methylated native ACTH. The kcat./Km ratios for methylated normal and deamidated ACTH were 43 and 185 M-1.s-1 respectively. These results indicate that PME recognizes native and deamidated methylated substrates as two different entities. This suggests that the methyl groups on native calmodulin and ACTH substrates may not be on the same amino acid residues as those on deamidated calmodulin and ACTH substrates.
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PMID:Mammalian protein methylesterase. Physical and enzymic properties. 254 48

The purpose of this study was to compare the control of adrenocorticotropin (ACTH) and corticosterone secretion in homozygous Brattleboro rats with their syngeneic controls, Long-Evans rats, and with rats of the Wistar strain. Plasma concentrations of ACTH and corticosterone were measured by radioimmunoassay in trunk blood, and corticotropin-releasing factor 41 (CRF-41), arginine vasopressin (AVP), and oxytocin were assayed in hypophysial portal vessel blood. Portal plasma was extracted with methanol for CRF-41 determination, and four different antisera and several different high-performance liquid chromatography (HPLC) systems were used to investigate AVP release. The peripheral plasma concentrations of ACTH and corticosterone were significantly higher in Long-Evans and homozygous Brattleboro than in Wistar rats. This difference was due, at least in part, to an approximately twofold greater release of CRF-41 into hypophysial portal blood of the Long-Evans and Brattleboro compared with Wistar rats. There was no significant difference between the strains in the output of oxytocin into portal blood. While no AVP could be detected in the neural lobe of homozygous Brattleboro rats, a small amount of AVP-like immunoreactivity was detected in unextracted hypophysial portal blood from homozygous Brattleboro rats. However, this AVP-like immunoreactivity was clearly distinct from authentic AVP in several HPLC systems, had no antidiuretic activity, and on gel filtration had a relative molecular mass greater than 5 kD. In contrast, the AVP-like immunoreactivity in hypophysial portal blood from Long-Evans rats co-eluted with authentic AVP in all HPLC systems tested.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of adrenocorticotropin control in Brattleboro, Long-Evans, and Wistar rats. Measurement of corticotropin-releasing factor, arginine vasopressin, and oxytocin in hypophysial portal blood. 285 6


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