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)

A highly purified preparation of high-molecular-weight adrenocorticotropic hormone (ACTH) was prepared from ovine pituitary glands by dilute acetic acid extraction, oxycellulose fractionation. Sephadex gel filtration, and affinity chromatography on immobilized alphap(1-39)ACTH antibodies. Two ACTH peptides of molecular weights of 24 000 and 34 000 were detected by sodium dodecyl sulfate-acrylamide gel electrophoresis in this preparation. It appeared that the immobilized antibodies adsorbed two forms equally well and could not distinguish between them under the conditions used. These two ACTH peptides were found to be present in crude extracts of ovine pituitary glands, indicating that they were not artifacts produced by the purification procedure. The high-molecular-weight forms of ACTH were found to be susceptible to degradation by tissue enzymes. They could be easily destroyed during the extraction, if precautions were not taken. Moreover, they were poorly adsorbed by oxycellulose which had been used for the adsorption of ACTH activity from crude preparations by most investigators. These properties probably accounted for the fact that high-molecular-weight forms of ACTH remained undetected until very recently.
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PMID:Purification and characterization of high-molecular-weight forms of adrenocorticotropic hormone of ovine pituitary glands. 19 94

In the pars intermedia of rat pituitary glands, two forms of a common precursor for corticotropin (ACTH) and beta-lipotropin with apparent molecular weights of 34,000 and 36,000 were resolved by sodium dodecyl sulfate/acrylamide gradient slab gel electrophoresis. High-performance liquid chromatographic analysis of [35S]methionine-labeled tryptic fragments of the two forms of the precursor revealed that both contained copies of ACTH-(1-8) and beta-lipotropin-(61-69) sequences. When biosynthetic studies were performed in the presence of tunicamycin, the 34,000- and 36,000-dalton forms were replaced by a peptide with an apparent molecular weight of 32,000. It was therefore concluded that the 34,000- and 36,000-dalton forms of the precursor represent two glycoprotein variants of similar polypeptides, differing in the number of asparagine-linked carbohydrate moieties. During pulse-chase incubations with [35S]methionine, the precursor forms were cleaved into two major groups of labeled products: (i) beta-endorphin and (ii) a mixture of ACTH fragments closely related to alpha-melanotropin. No ACTH-(1-39) was found at the end of a 2-hr chase period, suggesting that ACTH is not a significant hormone product of the rat pars intermedia.
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PMID:Concomitant synthesis of beta-endorphin and alpha-melanotropin from two forms of pro-opiomelanocortin in the rat pars intermedia. 22 77

Acrylamide is an efficient quencher of tryptophanyl fluorescence which we report to be very discriminating in sensing the degree of exposure of this residue in proteins. The quenching reaction involves physical contact between the quencher and an excited indole ring, and can be kinetically described in terms of a collisional and a static component. The rate constant for the collisional component is a kinetic measure of the exposure of a residue in a protein, and values ranging from 4 X 10(9) M-1 S-1 for the fully exposed tryptophan in the polypeptide, adrenocorticotropin, to less than 5 X 10(8) M-1 S-1 for the buried residue in azurin have been found. Static quenching is readily detected in proteins that are denatured, or contain only a single fluorophor. Quenching patterns for most multi-tryptophan containing proteins are difficult to analyze precisely, but qualitative information can, nevertheless, be extracted. Applications of this probing technique for monitoring protein conformational changes, such as the acid-induced expansion of human serum albumin, and inhibitor binding to enzymes, are presented. The value of this method lies in its ability to sense not only the steady-state exposure of a residue in a protein, but also its dynamic exposure.
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PMID:Exposure of tryptophanyl residues in proteins. Quantitative determination by fluorescence quenching studies. 125 18

The effect of acute and subchronic acrylamide treatment on levels of dopamine, serotonin, and their metabolites was determined in several brain regions of the rat. Concentrations of several neuropeptides and circulating hormones were also measured. Both a single and repeated doses of acrylamide resulted in elevated levels of 5-hydroxyindolacetic acid in all regions studied (frontal cortex, striatum, hippocampus, brain stem, and hypothalamus). Changes in regional content of other monoamines were much less pronounced. Turnover studies following pargyline blockage of monoamine oxidase, suggested results were due to increased rates of serotonin turnover in acrylamide-treated rats. Changes in neuropeptide levels were only detected in the hypothalamus where a single acrylamide treatment caused elevated levels of beta-endorphin and substance P, and in frontal cortex where met-enkephalin levels were higher after repeated acrylamide injection. Such repeated injection caused a major depression in plasma levels of testosterone and prolactin.
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PMID:Effect of acrylamide on neurotransmitter metabolism and neuropeptide levels in several brain regions and upon circulating hormones. 618 40

A macromolecular aggregate of corticotropin-beta-lipotropin common precursor had been observed in ovine pituitary preparations as an excluded fraction of Sephadex G-200 gel filtration. This fraction could not penetrate a 10% gel during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, when 2-mercaptoethanol or other disulfide-cleaving agents were not present in the buffer used to solubilize the protein preparation prior to the electrophoresis. On a 4.6% gel (acrylamide:bisacrylamide, 20:1), the material migrated as a diffuse band to a position between those of beta-galactosidase (Mr 130 000) and myosin (Mr 200 000). Both observations were consistent with an apparent Mr greatly in excess of that of the corticotropin-beta-lipotropin common precursor reported by many investigators. Neither 5% SDS nor 1% Triton X-100 could dissociate the macromolecular aggregate, but 2-mercaptoethanol and urea, either alone or in combination, were able to dissociate it to two main protein components, one of which was identified as corticotropin-beta-lipotropin with an apparent Mr of 34 000. The fact that urea alone could dissociate this macromolecular aggregate led us to believe that it might be a non-covalent aggregate and that 2-mercaptoethanol probably did not achieve the dissociation through the cleavage of an interchain disulfide bond but by bringing about conformational changes as a result of reduction of intrachain disulfide bonds so that aggregation became unfavorable. Moreover, the dissociation by urea or by 2-mercaptoethanol was found to be irreversible. The origin of the macromolecular aggregate of corticotropin-beta-lipotropin common precursor remains obscure.
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PMID:Characterization of a macromolecular aggregate of ovine pituitary corticotropin-beta-lipotropin common precursor. 626 48

Ovine corticotropin-beta-lipotropin common precursor was purified to homogeneity from commercial frozen ovine pituitary glands. A crude preparation was obtained following a procedure published elsewhere (Lee, T.H. and Lee, M.S. (1977) Biochemistry 16, 2824-2829) and was purified by gel filtration on Sephadex G-200 in the presence of 0.5% SDS and 0.1% 2-mercaptoethanol, and under an atmosphere of nitrogen. The gel filtration was repeated once. The partially purified preparation obtained from the second Sephadex G-200 gel filtration was further fractionated by preparative SDS-acrylamide gel electrophoresis, using immunoprecipitated and electrophoretically purified [125I]corticotropin-beta-lipotropin common precursor as a marker. The preparation was judged homogeneous by the appearance of a single protein band in analytical SDS-acrylamide gel electrophoresis, which exhibited both corticotropin and beta-lipotropin immunoreactivities, and a single symmetrical peak in high-pressure liquid chromatography on a reverse phase C18 column. The isolated ovine corticotropin-beta-lipotropin common precursor possessed specific activities of 116 micrograms of immunoreactive corticotropin and 210 micrograms of immunoreactive beta-lipotropin per mg of protein, equivalent to 89 and 62% of theoretical values, respectively. The amino acid composition of the homogeneous preparation was determined.
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PMID:Isolation of corticotropin-beta-lipotropin common precursor from ovine pituitary glands. 674 90

This study reports the biosynthesis of two forms of pro-opiomelanocortin in the pars intermedia of the pituitary gland of the African clawed toad Xenopus laevis. The two forms could be resolved by dodecyl sulphate gel electrophoresis on a 9-16% acrylamide gradient and their molecular weights were 38200 and 37300. Incubation of neurointermediate lobes with [3H]glucosamine followed by tryptic digestion of the newly synthesized glycoproteins, revealed that both prohormones have only one glycosylated site, namely within the region corresponding to gamma 3-melanotropin. Biosynthesis of proteins in lobes treated with tunicamycin to prevent glycosylation again resulted in the production of two pro-opiomelanocortins (Mr 35000 and 34200), indicating that the two forms differ in their primary structure. This notion was corroborated by the results of tryptic mapping of the newly synthesized prohormones. The maps showed that the primary structures of the two forms of pro-opiomelanocortin differ in at least two parts of the molecules, one part concerning the endorphin region.
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PMID:Biosynthesis of two structurally different pro-opiomelanocortins in the pars intermedia of the amphibian pituitary gland. 712 82

Fluorescence emission from the single tryptophan residues of two melanocyte stimulating hormones, alpha-MSH and delta-MSH, and their quenching kinetics were studied in aqueous solution and in reverse micelles of AOT/water/isooctane. Incorporation into micelles caused blue shifted and narrower emission peaks, altered quantum yields and considerably enhanced anisotropies for both peptides when compared to emission from bulk water. The variation of emission parameters with micellar water content was interpreted to suggest that while the tryptophan in alpha-MSH lies in close vicinity of the water-AOT molecular interface, that in delta-MSH is solubilized in the central water pool. Total emission intensity decays followed complex (biexponential) kinetics in both aqueous and micellar media. Although the mean lifetimes for both peptides were always nearly the same, the average rotational correlation times in micelles for alpha-MSH were three times as much as those for delta-MSH. Stern-Volmer plots obtained using acrylamide and CCl4 as quenchers localized in the micellar and organic pseudophases, respectively, were non-linear and dependent on emission wavelength. Quenching by acrylamide was more efficient for delta-MSH than for alpha-MSH, while the opposite was true for quenching by CCl4. The implication of this result for localization of the peptides in micelles was consistent with the earlier one emerging from these studies.
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PMID:Fluorescence study of melanocyte stimulating hormones in AOT reverse micelles. 768 63

This paper presents a quantitative and sensitive assay for the measurement of chemosensory behavior in Tetrahymena. The two-phase assay is easy to perform in large quantities, so a variety of compounds can be screened under comparable conditions. A suspension of 2 x 10(5) cells ml-1 (the upper phase) is starved for 20-40 h and then gently placed on top of a 5% solution of Metrizamide (the lower phase) in a disposable microcuvette. The optical density of the lower phase is monitored at 600 nm with an automated spectrophotometer at selected time points. Optimum sensitivity of the assay is achieved when the cells slowly but continuously enter the lower phase, so that about 5% of them will be in the lower phase within 30 min. Optimal chemosensory responses occurred in Tetrahymena thermophila at about 25 degrees C. The response was delayed at 15 degrees C and markedly reduced at 35 degrees C. The data suggest three bases for quantifying the response in the assay: (1) initial slope of the absorbance versus time; (2) final maximal absorbance within the time period of measurement; and (3) signal-to-noise ratio (S/N) at a fixed time. We have quantified--in terms of S/N--the chemosensory responses in Tetrahymena for the following compounds: beta-endorphin, fibroblast growth factor, insulin, and platelet-derived growth factor (PDGF); these substances were active in nanomolar concentrations, and the maximal S/N was between 3 and 5.1. Acetylcholine was active only in millimolar concentrations; maximal S/N was 4.1 at 1 mM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An improved quantitative assay for chemokinesis in Tetrahymena. 791 98

The peptide hormone adrenocorticotropin and a related peptide were studied in solution and in interaction with a model system of membranes (small unilamellar vesicles of dipalmitoylphosphatidylcholine and 17% dimyristoylphosphatidylglycerol) via fluorescence spectroscopy. In aqueous solution, intramolecular distances between the fluorescent residues R(Tyr2-Trp9) = 9.2 A and R(Trp9-Tyr23) > or = 18 A were obtained, in agreement with molecular models. Interaction of the peptide with the negatively charged membrane is evident from the alteration of the Trp photophysical parameters (quantum yield, fluorescence spectra and anisotropy), with a partition constant between the lipidic and aqueous phase of Kp = 1-2 x 10(3). The existence of two populations of Trp in the membrane, which are distinctly accessed by acrylamide, was concluded from the tryptophan fluorescence quenching study; the two fractions are located near the membrane interface as inferred from its fluorescence quenching by the 5-doxylstearate and 16-doxylstearate lipophilic quenchers. This result is further supported by energy transfer experiments to the 3-(9-anthroyloxyl)stearic acid and 12-(9-anthroyloxyl)stearic acid probes.
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PMID:Interaction of the peptide hormone adrenocorticotropin, ACTH(1-24), with a membrane model system: a fluorescence study. 847 75


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