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)

The decay of the indole triplet of single tryptophan-containing proteins and model compounds can be readily determined at room temperature in solution by monitoring the triplet absorption or emission following an exciting laser pulse. The dioxygen triplet quenching constants, can be measured for all these molecules and compared to the analogous singlet values determined by fluorescence methods. The dioxygen triplet quenching constant (tkq) ranged from a high of 5.1.10(9) M-1.s-1 for the exposed indole of corticotropin to a low of 0.1.10(9) M-1.s-1 for the buried indole of asparaginase. The ratio of these values with their respective dioxygen singlet quenching constants (skq), tkq/skq, ranged from 0.3 to 0.6 for aqueous exposed polypeptide indoles. For globular proteins the tkq/skq value is observed to be 0.2 +/- 0.1. This lower value for protein indoles is not attributable to 'bulk' environmental or hydrogen bonding effects, since the magnitude of tkq/skq (= 0.5 +/- 0.1) for model indoles was independent of solvent dielectric constant, polarity, and proticity. Temperature-dependence studies were done to test whether tkq could be used to characterize the nature of the protein matrix. The activation energy (Ea) for tkq was found to be 11 +/- 2 kcal/mol for most proteins. This Ea was independent of whether the indole side-chain was solvent exposed or buried in the non-aqueous protein interior. Large Ea values were also obtained for model indoles, naphthalene and nalidixic acid, dissolved in water, whereas the same compounds dissolved in 95% ethanol exhibited much smaller Ea values. These data, in combination with the observation that the tkq of model indoles is insensitive to changes in solvent viscosity, indicate that dioxygen quenching at the triplet level can not be easily used to characterize the dynamics of proteins.
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PMID:Determination of the dioxygen quenching constant for protein and model indole triplets. 319 Nov 39

Plasma levels of catecholamines and neuropeptides (met-enkephalin, ME; neurotensin, NT; neuropeptide Y, NPY; peptide YY, PYY; vasoactive intestinal polypeptide, VIP; cholecystokinin, CCK; bombesin, BMB) were examined in the femoral artery (FA), adrenal vein (AD), and portal vein (PV), in eight cats under halothane anesthesia at baseline (S1), at the end of a 2-hr ligation period of the major splanchnic arteries (celiac trunk, superior and inferior mesenteric arteries) (S2), immediately (S3) and 30 min (S4) after splanchnic reperfusion, and after the administration of naloxone (1 mg/kg, i.v.) (S5). During S2, there was a significant increase in portal vein VIP levels, while the other variables (hemodynamics, hormone levels) remained unchanged. During early shock (S3), significant (10- to 30-fold) increases in adrenal secretion of all catecholamines, ME, NT, NPY, and PYY occurred, while VIP and PYY were significantly released into the PV, and two- to tenfold increases in femoral artery catecholamine and ME levels were observed. Later shock (S4) led to a further fivefold increase, compared to S3, in adrenal release of norepinephrine (NE), dopamine (DA), and ME. Following naloxone administration (S5), the adrenal medullary release of NE, epinephrine (EPI), DA, NT, and NPY was significantly (twofold) increased; however, the animals' hemodynamic situation did not improve.
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PMID:Adrenal and intestinal secretion of catecholamines and neuropeptides during splanchnic artery occlusion shock. 321 33

An observation from high-pressure liquid chromatography (HPLC) suggesting that monkey beta-endorphin (BE) was chemically different from human or rat BE was investigated by determining the cDNA sequence for the monkey pro-opiomelanocortin (POMC) precursor. A full-length cDNA for POMC was isolated from a Macaca nemestrina whole pituitary cDNA library. The longest open reading frame predicts a 264-residue polypeptide exhibiting the basic structure of POMC that is closely homologous to the human counterpart. The monkey BE sequence apparently diverged from the human sequence after the latter had made the His-27 to Tyr-27 change but prior to the Gln-31 to Glu-31 transition, leaving it more hydrophobic than rat or human BE, consistent with its chromatography on reverse-phase HPLC. Comparison of the monkey POMC precursor with those of other species highlights conserved domains, presumably reflecting regions of physiological activity that await elucidation.
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PMID:Characterization of pro-opiomelanocortin cDNA from the Old World monkey, Macaca nemestrina. 322 86

Peptidylglycine alpha-amidating activities from rat pituitary, brain and small intestine were compared, utilizing C-terminal analogues of vasoactive intestinal polypeptide (VIP), D-Tyr-Leu-Asn-Gly and D-Tyr-Asn-Gly, and C-terminal analogue of alpha-MSH, D-Tyr-Val-Gly. The three tissues had enzymic activities capable of converting the glycine-extended peptides to the corresponding alpha-amidated ones. In other words, all of three peptides could serve as substrates for the enzymes from both neural and gastrointestinal tissues. The activities were stimulated in the presence of copper and ascorbate; the optimal concentration of each cofactor was roughly equal for the three enzymes; similar pH profiles (a neutral pH optimum at 6.5-7 and another one at 8-8.5) were also observed. Desamide VIP-Gly was proved to be a potent inhibitor of the alpha-amidating activities from the tissues, but VIP was not, indicating that the alpha-amidating enzymes from these tissues in common have a recognition site for the C-terminal glycine of the glycine-extended precursor regardless of the length and nature of the sequence. No fundamental differences were observed between the catalytic properties of the alpha-amidating activities from these three tissues, raising the possibility that similar enzymes, which may or may not be a single species, are functioning in tissues that produce alpha-amidated polypeptides in vivo.
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PMID:Characterization of peptidylglycine alpha-amidating activities in rat pituitary, brain and small intestine using glycine-extended C-terminal analogues of vasoactive intestinal polypeptide as substrate. 323 97

The divalent cation barium was used to study the role of calcium in coupling neuropeptide secretion and biosynthesis following secretagogue stimulation of bovine chromaffin cells. Barium chloride (0.1-2.5 mM) stimulated in a dose-dependent manner the secretion of met-enkephalin (up to 20% of intracellular peptide content) and increased the total amount (cell plus medium content) of met-enkephalin and vasoactive intestinal polypeptide (VIP) 2- to 3-fold after 72 hours. A greater than six-fold increase in proenkephalin mRNA (mRNA(enk)) was observed by 24 hours following barium stimulation. The voltage-sensitive calcium channel blocker D600 inhibited the barium-stimulated secretion of enkephalin and blocked the stimulation of VIP biosynthesis and mRNA(enk). Reducing calcium in the medium resulted in an enhancement of barium-stimulated release of both peptides, but blocked the induction of their biosynthesis. The data indicate that calcium targets involved in secretion can be activated by barium or calcium while calcium targets involved in biosynthesis specifically require calcium. It is therefore proposed that pathways leading to peptide secretion and biosynthesis in the adrenal diverge just after secretagogue-stimulated calcium influx.
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PMID:Calcium requirements for barium stimulation of enkephalin and vasoactive intestinal peptide biosynthesis in adrenomedullary chromaffin cells. 336 36

Corticotropin-releasing factor (CRF), a 41 amino acid polypeptide, has been isolated from ovine hypothalamic extracts, sequenced, and synthesized. It has a high potency for stimulating the secretion of corticotropin-like and beta-endorphin-like immunoactive substances in vitro and in vivo in laboratory animals and humans. The high concentration of CRF-like immunoactivity in hypophyseal portal plasma supports the hypothesis that CRF is the physiological hypothalamic factor. Human and rat CRF (rCRF) also have been purified and synthesized. They have an 83% sequence homology with ovine CRF (oCRF). oCRF-like activity has been found in human hypothalamus, pituitary stalk, posterior pituitary, thalamus, cerebral cortex, cerebellum, pons, medulla oblongata, spinal cord and in the adrenal, lung, liver, stomach, duodenum and pancreas. oCRF-like activity also has been found in the human placenta and in tissues producing ectopic ACTH. The action of CRF can be potentiated by vasopressin, oxytocin, epinephrine, norepinephrine, VIP, and angiotensin II. Intracerebroventricular administration of CRF in the rat produces prolonged elevations of plasma epinephrine, norepinephrine, glucose and glucagon; elevates mean arterial pressure and heart rate; increases motor activity and exploration in familiar surroundings and oxygen consumption; and decreases feeding and sexual behavior. Testing with CRF has enabled the separation of patients with hypothalamic and pituitary adrenal insufficiency. The CRF stimulation test has been useful in distinguishing pituitary from ectopic causes of Cushing's disease. The distribution of CRF within and beyond the hypothalamus provides an anatomical context for the observation that CRF can simultaneously activate and coordinate metabolic, circulatory and behavioral responses that are adaptative in 'stressful' situations. CRF not only stimulates the pituitary-adrenal axis in man, but it also influences several aspects of CNS function which may be of relevance to psychiatric illnesses.
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PMID:Corticotropin-releasing factor (CRF)--a review. 353 10

The immunohistochemical demonstration of neurofilament (NF) polypeptide was used to identify nerves in a series of 17 pituitary adenomas. NF-positive fibres were present in two out of five corticotroph adenomas sited deep in the anterior lobe, in one out of five sited in the intermediate zone and in two out of seven non-corticotroph adenomas. Such nerve fibres were often seen in relation to blood vessels. The distribution of alpha-MSH immunoreactive cells was examined in 25 normal pituitaries and in 23 cases of Cushing's disease. Such cells were scattered throughout the normal gland and there was no increase in numbers in pregnancy. alpha-MSH was demonstrated in 18 corticotroph adenomas in Cushing's disease. There was no correlation with the site of the tumour or the presence of nerve fibres. alpha-MSH cells were distributed normally in the para-adenomatous gland. Crooke's hyaline change and alpha-MSH coexisted in some corticotrophs. These findings support the concept that 'intermediate lobe' function, as found in animals, has no discrete anatomical location in man.
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PMID:A study of intermediate lobe differentiation in the human pituitary gland. 354 73

We have constructed three different truncated versions of diphtheria toxin (a 535-amino-acid polypeptide) which correspond to the N-terminal 290, 377, and 485 amino acids of the toxin. These lengths include one, three, and all four of the putative membrane-spanning sequences of the toxin which are thought to play a role in the translocation of fragment A into cells. Each of these three genes has been modified at its 3' end to code for a C-terminal cysteine (to allow for disulfide linkage of a targeting ligand) or a gene fusion with alpha-melanocyte-stimulating hormone. We have also substituted the native diphtheria tox promoter (ptox) with the lambda pR promoter in an effort to overexpress these proteins. The truncated genes are expressed in Escherichia coli from both the tox promoter in a constitutive fashion and from the pR promoter by using the heat-inducible cI857 repressor. The clones produce proteins which react with anti-diphtheria toxin serum, which migrate at the anticipated Mr on Western blots, and which have ADP-ribosyltransferase activity. Constitutive synthesis from ptox leads to severe proteolytic degradation even in a protease-deficient strain. High-level expression from the pR promoter in the same lon htpR strain allows the full-length polypeptides to accumulate but also stops the growth of the cells. It appears that removal of as few as 50 amino acids from the C-terminus of diphtheria toxin alters its conformation, making it a target for proteases and causing overexpression lethality in the host cells.
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PMID:Cloning and expression in Escherichia coli of three fragments of diphtheria toxin truncated within fragment B. 354 95

Proopiomelanocortin (POMC), the common precursor to beta-endorphin and alpha-melanocyte-stimulating hormone synthesized in rat intermediate lobe cells, exhibits both charge and size heterogeneity on two-dimensional gels. Pulse-labeling and pulse-chase studies revealed that this heterogeneity is due to co- and post-translational modifications of a single common polypeptide. Short 5-min-pulse incubation with [3H]phenylalanine allowed the preferential labeling of two major forms characterized by an identical isoelectric point (8.2), but slightly different apparent molecular weights (MW = 34,000 and 36,000). These peptides could be labeled with [3H]mannose and the analysis of their tryptic fragments by high-pressure liquid chromatography revealed that they correspond to polypeptides bearing one or two N-linked carbohydrate side chains. Accumulation of more acidic forms was observed during subsequent chase incubations in the absence of phenylalanine. These acidic forms were shown to incorporate sulfate and (or) phosphate groups. Sulfation and phosphorylation occurred on POMC within 5 min after its synthesis and were concomitant with the processing of the N-linked carbohydrates from the high mannose to the complex structure. Finally, partial digestion of the phosphorylated and nonphosphorylated analogs of POMC with either Staphylococcus aureus (V8 strain) protease or chymotrypsin suggests that the presence of a phosphate group may alter POMC sensitivity to exogenously added proteases.
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PMID:Posttranslational modifications of proopiomelanocortin in rat intermediate lobe cells. 355 99

Carcinoid tumors of the middle ear are rare, with only three previously reported cases. The authors report the light and electron microscopic and immunohistochemical features of two carcinoid tumors that occurred in a 34-year-old female and a 21-year-old male. Both presented with unilateral hearing loss. By light microscopic examination, both were characterized by trabecula of tall columnar cells with basal nuclei and no mitotic activity. Electron microscopic examination demonstrated large numbers of pleomorphic neurosecretory granules, perinuclear aggregates of intermediate filaments, cell junctions, and surface microvillous processes. Some cells contained intermediate filaments forming tonofilaments and lacked secretory granules. These cells stained for cytokeratin by immunoperoxidase and separated the neuroendocrine cells from the underlying basal lamina. The cells in this tumor stained for the molluscan cardioexcitatory peptide. Cells in both tumors also stained for pancreatic polypeptide. Neither case stained for lysozyme, insulin, glucagon, somatastatin, gastrin, substance P, thyroid-stimulating hormone, adrenocorticotropic hormone, Met-enkephalin, Leu-enkephalin, neuropeptide Y, peptide YY, neurotensin, Bombesin, serotonin, neuron-specific enolose, glial and neural filaments, S-100 protein, cholecystokinin, beta-endorphin, beta-human chorionic gonadotropin, luteinizing hormone/follicle-stimulating hormone, vasoactive intestinal polypeptide, prolactin or calcitonin. Carcinoid tumor of the middle ear can be distinguished from paraganglioma and middle ear adenoma.
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PMID:Carcinoid tumors of the middle ear. 357 33


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