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

This study evaluates the presence of proopiomelanocortin (POMC)-related peptides in four embryos and eight fetal pituitaries starting from 5 to 25 weeks of pregnancy. Moreover, fetal membranes (amnion and chorion) were also investigated. Freshly collected samples were boiled in acetic acid to destroy enzymes, homogenized and submitted to high performance liquid chromatography (linear gradient from 25 to 40% acetonitrile in 0.01 M HCI, in 15', 1.5 ml/min). The collected fractions were tested for the presence of beta-lipotrophin (beta-LPH), beta-endorphin(beta-EP), gamma-endorphin(gamma-EP) through RIAs. beta-EP and beta-LPH were detected from 7 weeks of pregnancy while gamma-EP appeared later. Only the cephalic portion of the embryos contained the peptides where beta-LPH predominates while no immunoreactivity was detected in the rostral one. In the fetal pituitary there is a progressive increase of gamma-EP according to the gestational age and both beta-EP and beta-LPH showed a trend toward constancy in the 15-25 week range. Amnion and chorion contain a significant amount of the three peptides. Their ontogenesis starts earlier than in the embryo; beta-LPH or beta-EP were detected at 5 weeks of pregnancy. In both tissues beta-EP was higher in the first than in the second trimester. These data demonstrate a different pattern of POMC ontogeny and processing between the conceptus and his environment. This suggests that the POMC-related opiod system of the fetus and of fetal adnexes are independent of each other, possibly subserving to different functions.
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PMID:Proopiomelanocortin-related peptides in feto-placental structures throughout pregnancy. 243 58

Thirteen patients with pain from various causes were treated by electroacupuncture for 30 min. Cerebrospinal fluid (CSF) was obtained before and after treatment. Opioid-like substances in the CSF were fractionated by high pressure liquid chromatography and assayed by competitive receptor binding using a mu-specific radioligand, [D-ala2, MePhe4, gly-ol5]-enkephalin (DAGO). Opioid activity, associated with a fraction, eluted at 18-20% acetonitrile, consistently showed an increase in level after acupuncture. Two other fractions eluted at larger concentrations of acetonitrile also increased significantly after acupuncture; however the increase was not consistently observed in every patient. Measurements of beta-endorphin and dynorphin by radioimmunoassay indicated that 80 and 60% of the patients, respectively, had a higher level of these peptides after acupuncture. The nature of the opioid activity, eluted at 18-20% acetonitrile is unknown; however a small amount of it could be found in various parts of the brain of rat.
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PMID:Opioid-like activity in the cerebrospinal fluid of pain patients treated by electroacupuncture. 257 98

Gel-permeation high-performance liquid chromatography (GP-HPLC) columns provide rapid high-resolution separations but are frequently limited to analytical tasks because the injection volumes must be small. The reduction of volume required for the loading of solutes can often be impractical and lead to poor recoveries. We have developed a trace-enrichment technique to circumvent this problem. By placing a Waters Guard Pak within the loop of a Valco injector and connecting a pump to the injection port it is possible to concentrate proteins and peptides onto the guard column from relatively large volumes. Enrichment onto a reversed-phase guard column insert is achieved by loading solutes in an aqueous solution or one of low organic solvent concentration. Provided that the GP-HPLC is mean-while equilibrated with a solvent system of sufficiently high organic solvent concentration (i.e., 40% acetonitrile containing 0.1% trifluoroacetic acid) it is possible to elute material that has been loaded in this manner by simply placing the injection loop in line with the column. The solvent strength abruptly increases and the peptide or protein sample is loaded onto the column in a very small volume. We have applied this loading principle to both analytical and semipreparative problems. The amino-terminal fragment of pro-opiomelanocortin (POMC) has been extracted from a single human fetal pituitary (18 weeks gestation) and characterized in terms of its molecular weight. This study indicated that no proteolytic processing of the amino-terminal fragment of POMC takes place at this stage in development. In a larger scale application the amino-terminal fragment of POMC was purified from bovine anterior pituitaries.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A trace-enrichment technique for the loading of gel-permeation high-performance liquid chromatography columns. 267 75

In order to evaluate the expression of the opioid precursor proopiomelanocortin (POMC) in the ovarian follicle, we measured 6 of its main end-products in 23 follicular fluids. We coupled high performance liquid chromatography (HPLC) to specific radioimmunoassays. Seven follicles were immature (diameter less than 9 mm), 10 were obtained from superovulated patients during an in vitro fertilization-embryo transfer program (greater than 22 mm) and six were persistent follicles, collected during the luteal phase [15-31 mm, luteinized unruptured follicles (LUF)]. Follicular fluids were extracted by mean of Sep-pak cartridges and then purified by HPLC with a reverse-phase C-18 column eluted in a linear gradient with acetonitrile/0.01 M hydrochloric acid (from 18:82 to 40:60). Fractions were tested with specific antisera for ACTH (1-39), alpha-MSH, beta-lipotropin (beta-LPH), beta-endorphin (beta-EP) and gamma-endorphin (gamma-EP) immunoreactivities. No presence of beta-LPH, beta-EP and ACTH was confirmed, while gamma-EP, alpha-MSH and des-alpha-MSH were detected for the first time in follicular fluid. In every class of follicles shorter chain peptides predominate over their longer chain precursor. Immature follicles are characterized by the highest amounts of gamma-EP, ACTH, alpha-MSH and des-alpha-MSH if compared to superovulated and LUF. On the contrary, beta-EP amount was highest after superovulation. Apart from this finding, peptide levels in superovulated patients and LUF are similar.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of proopiomelanocortin-related peptides in human follicular fluid. 285 46

The bandwidths of several polypeptides related to human beta-endorphin have been investigated with different n-alkylsilica stationary phases and different elution gradients of 0.1% trifluoroacetic acid-water-acetonitrile mobile phases. In particular, we have examined the influence of changes in the gradient steepness parameter, b, on peakwidth with five different octadecylphases, chemically bonded to porous spherical silica particles of nominally 4 micron and 6 micron average particle diameter, respectively. The effect on the zone dispersion of these polypeptide solutes as the average pore diameter of the silica matrix was increased from 7.3 nm to 30 nm with stationary phases of similar ligand densities packed into columns of identical configuration has been further documented. The experimental data on solute bandwidths and peak capacities are comparable with the corresponding bandwidth and peak capacity values calculated from analytical equations, derived from the general plate height theory and from gradient elution theory. These comparisons clearly demonstrate that anomalous bandbroadening phenomena may occur when polypeptides are eluted with steep gradients, i.e. with gradients of large b values. Moreover, as the relative chromatographic residence times of beta-endorphin peptides capable of forming a C-terminal amphiphilic secondary structures is increased, i.e. as the dwell times and median capacity factors, k, for such peptides are increased, significant divergencies arise between the observed peakwidth behaviour and the behaviour predicted by analytical relationships which describe either the dependency of peak bandwidth (as 4 sigma v) on the gradient steepness parameter, b, or the dependency of peak capacity on gradient time, tG, median capacity factor, k, and the Knox parameter, C, respectively. The importance of these divergences from the predicted bandwidth and peak capacity behaviour for polypeptides separated on reversed phases, and for resolution optimisation in particular, is evaluated. These investigations thus enable further assessment of the quantitative relevance of current models that describe polypeptide zone migration under gradient elution reversed-phase chromatographic conditions in which solute-dependent slow equilibria, mediated by conformational or solvation effects, may still occur.
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PMID:High-performance liquid chromatography of amino acids, peptides and proteins. LXVII. Evaluation of bandwidth relationships of peptides related to human beta-endorphin, separated by gradient-elution reversed-phase high-performance liquid chromatography. 293 99

Ten polypeptides that stimulated the release of corticotropin from superfused rat pituitary cells and that are structurally related to porcine corticotropin-releasing factor were isolated from porcine hypothalami. The purification was carried out by gel filtration followed by reversed-phase HPLC using trifluoroacetic acid or heptafluorobutyric acid as the ion-pairing agent in water/acetonitrile solvent systems. The purified peptides were homogeneous by chromatography and by sequence analysis. One major polypeptide was characterized. Its structure is -H-Ser-Glu-Glu-Pro-Pro-Ile-Ser-Leu-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Gl u-Val -Leu-Glu-Met-Ala-Arg-Ala-Glu-Gln-Leu-Ala-Gln-Gln-Ala-His-Ser-Asn-Arg-Lys -Leu-Met-Glu-Asn-Phe-NH2 [Patthy, M., Horvath, J., Mason-Garcia, M., Szoke, B., Schlesinger, D. H. & Schally, A. V. (1985) Proc. Natl. Acad. Sci. USA 82, 8762-8766]. This 41-amino acid sequence is thought to represent porcine corticotropin-releasing factor. Based on automated gas-phase sequencing of the intact and CNBr-cleaved peptides, amino acid analysis, and carboxypeptidase Y digestion, the other nine polypeptides were found to be structurally similar to this 41-amino acid sequence. Modifications of this structure include deamidation of glutamine at position 26 or 29, oxidation of methionine at positions 21 and/or 38, a blocked N terminus, and deletion of phenylalanine amide at the C terminus. Eight of these nine modified peptides retained significant corticotropin-releasing factor activity as shown by the stimulation of corticotropin release from superfused rat and pig pituitary cells. Some of these peptides may be present in pig hypothalami, while the others could have been produced during the isolation.
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PMID:Purification and characterization of peptides with corticotropin-releasing factor activity from porcine hypothalami. 301 Mar 25

In this method for rapid separation of beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) in plasma, most of the plasma proteins in a 0.5- to 2.0-mL sample of plasma are precipitated with acetonitrile at pH 4.7. beta-EP and beta-LPH in the supernate are completely separated by liquid chromatography on a cation-exchange column, with gradient elution with volatile buffers, and are eluted in 1.5- to 2.0-mL volumes. After lyophilization, the redissolved beta-EP and beta-LPH are determined by radioimmunoassay. The respective mean concentrations of immunoreactive beta-EP and beta-LPH in plasma of nonpregnant women were 4.0 (SD 2.0) and 5.1 (SD 3.0) pmol/L; during labor, 33.3 (SD 25) and 69.6 (SD 41) pmol/L; and in venous plasma from umbilical cords after spontaneous labor, 38.6 (SD 18) and 38.7 (SD 19) pmol/L.
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PMID:Determination of plasma beta-endorphin and beta-lipotropin by cation-exchange liquid chromatography and radioimmunoassay. 315 1

Calmodulin, a ubiquitous Ca2+-binding regulatory protein, is phosphorylated exclusively on tyrosine-99 in an insulin-dependent manner by wheat germ lectin-purified preparations of insulin receptors from rat adipocyte plasma membranes. Calmodulin is phosphorylated in the presence of polylysine, histone Hf2b, and protamine sulfate, but not in the absence of these cofactors or in the presence of other basic compounds known to interact with calmodulin, such as mellitin, myelin basic protein, chlorpromazine, trifluoperazine, substance P, glucagon, polyarginine, mastoparin, beta-endorphin, spermine, spermidine, and putrescine. The incorporation of 32P into calmodulin, expressed in terms of moles of phosphate per moles of calmodulin and assayed at calmodulin concentrations of 1.2 and 0.06 microM, is 0.023 + 0.002 and 0.046 + 0.006, respectively. This low stoichiometry is likely due to the relative impurity of the receptor preparation, as similar studies not shown here, using highly purified human insulin receptors, yield a stoichiometry of 1 mol phosphate/mol calmodulin. The time course of phosphorylation is characterized by a short initial lag phase of approximately 5 min, a rapid linear rate from approximately 5 to 40 min, with a steady state of 32P incorporation being approached at approximately 60 min. The K0.5 for ATP is 104 + 18 microM. Phosphorylated calmodulin is partially purified by HPLC on a C4 column using a trifluoroacetic acid/acetonitrile gradient solvent system. Phosphoamino acid analysis and limited thrombin digestion were used to determine that the site of insulin-induced phosphorylation of calmodulin is exclusively on tyrosine-99 regardless of the basic protein cofactor used. Phosphorylated calmodulin does not exhibit the characteristic Ca2+ shift normally observed with calmodulin in electrophoretic gels, an observation that is consistent with this modification affecting the biological activity of the molecule. Thus, the tyrosine phosphorylation of calmodulin represents a potentially important post-translational modification altering calmodulin's ability to regulate a variety of enzymes involved in growth, differentiation, and metabolic regulation.
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PMID:The in vitro phosphorylation of calmodulin by the insulin receptor tyrosine kinase. 341 47

The gradient retention behaviour in reversed-phase high-performance liquid chromatography of a series of polypeptides related to human beta-endorphin has been investigated using different n-alkylsilica stationary phases and 0.1% trifluoroacetic acid in water-acetonitrile as mobile phase. In particular, the influence of changes in gradient time and flow-rate on retention parameters has been assessed with five different porous octadecylsilica phases with average particle diameters of 4 microns and 6 microns. Decreasing the pore size from 30 nm to 7.3 nm resulted in decreased S and log k'o values for most solutes. The effect of changes in the gradient steepness parameter, b, on the bandwidth behaviour of these polypeptides has also been investigated. Anomalous band-broadening was observed for very steep and very shallow gradients, i.e. b greater than 0.7 or b less than 0.2. The significance of these results is discussed in relation to the presence of hydrophobic domains in the linear sequence, the probability of the formation of highly stabilised secondary structures and the possible involvement of multiple folded forms of a single solute in the chromatographic performance of these polypeptides.
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PMID:High-performance liquid chromatography of amino acids, peptides and proteins. LXXIII. Investigations on the relationships between molecular structure, retention and band-broadening properties of polypeptides separated by reversed-phase high-performance liquid chromatography. 365 34


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