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)

Systematic analysis of the hydrolysis of benzyloxycarbonyl (Cbz)-dipeptides by cathepsin A [EC 3.4.12.1] purified from rat liver lysosomes showed that multiple forms of cathepsin A preferentially cleave peptide bonds with leucine, methionine, and phenylalanine. Cbz-Met-Met, -Met-Phe, -Phe-Met, and -Phe-Ala were hydrolyzed 6 to 8 times faster than the standard substrates, Cbz-Glu-Phe and Cbz-Glu-Tyr. The pH optima of the hydrolyses were 4.6 to 5.8. Hydrolysis of peptide bonds with glycine, isoleucine, and proline was very slow, but the rate depended on the nature of the adjacent amino acids. Proteins such as albumin, cytochrome c, gamma-globulin, hemoglobin, histone, myoglobin, and myosin were scarecely degraded. Peptide hormones, such as glucagon and adrenocorticotropic hormone (ACTH) were hydrolyzed markedly with optimum pH's of 4.5 and 4.6, respectively. Angiotensin I, II, bradykinin, Lys- and Met-Lysbradykinin (kallidin and Met-kallidin), and substance P were also hydrolyzed at appreciable rates. pH optima for these peptide hormones were 5.2 to 5.6. On the other hand, insulin and its A chain, luteinizing hormone-releasing hormone (LH-RH), oxytocin and vasopressin were cleaved slowly. In the hydrolyses of glucagon and other peptides, multiple forms of rat liver lysosomal cathepsin A again showed a carboxypeptidase nature, cleaving peptide bonds sequentially from the carboxyl terminal. Almost all of the amino acids were cleaved on prolonged incubation. Vaso-activites of angiotensin II and bradykinin were rapidly lost on hydrolysis by cathepsin A. Lysosomal cathepsin C [dipeptidylaminopeptidase I, EC 3.4.14.1] also activated angiotensin II, but did not inactive bradykinin. Cathepsin A, therefore, can be regarded as one of the lysosomal angiotensinases and kinases. No distinct differences were observed between the multiple forms of cathepsin A in these hydrolyses and inactivations of peptides.
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PMID:Studies on cathepsins of rat liver lysosomes. III. Hydrolysis of peptides, and inactivation of angiotensin and bradykinin by cathepsin A. 1 61

Gangliosides inhibit 125I-labeled thyrotropin binding to the thyrotropin receptors on bovine thyroid plasma membranes, on guinea pig retro-orbital tissue plasma membranes, and on human adipocyte membranes. This inhibition by gangliosides is critically altered by the number and location of the sialic acid residues within the ganglioside structure, the efficacy of inhibition having the following order: GD1b greater than GT1 greater than GM1 greater than GM2 = GM3 greater than GD1a. The inhibition results from the interaction of thyrotropin and gangliosides, rather than the interaction of membrane and gangliosides. Fluorescence studies show that the inhibition is associated with a distinct conformational change of the thyrotropin molecule and that the progression from a "noninhibitory conformation" to an "inhibitory conformation" parallels exactly the order of effectiveness in inhibiting 125I-labeled thyrotropin binding. The ganglioside inhibition of 125I-labeled thyrotropin binding appears to be hormonally specific in that it is not affected by albumin, glucagon, insulin, prolactin, follicle-stimulating hormone, growth hormone, or corticotropin. The possibility that a ganglioside or ganglioside-like structure is a component of the thyrotropin receptor is suggested by the finding that gangliosides more complex than N-acetylneuraminylgalactosylglucosylceramide are present in bovine thyroid membranes in much higher quantities than have been previously found in extraneural tissue. The finding that the B component of cholera toxin, which also interacts with gangliosides, has a peptide sequence in common with the beta subunit of thyrotropin, suggests that thyrotropin and cholera toxin may be analogous in their mode of action on the membrane.
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PMID:Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors. 17 57

Porcine beta-melanocyte-stimulating hormone and angiotensin II were examined as acceptors in the reaction catalyzed by arginyl-tRNA-protein transferase. Both inhibited enzymatic transfer of [14C]arginine from tRNA to bovine albumin. Inhibition was competitive with albumin and the K-i values were, respectively, 15 and 0.8 muM. The expected arginylated compounds were isolated and characterized. Beta-melanocyte-stimulating hormone and its arginylated product had identical activities in the frog epithelium bioassay. In contrast, the biological activity of angiotensin II was diminished by enzymatic arginylation. The pressor effect of the arginylated derivative on anesthetized rats and its activity on the isolated rat uterus were, respectively, approximately 60% and 20% of those found for the unmodified peptide.
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PMID:Enzymatic arginylation of beta-melanocyte-stimulating hormone and of angiotensin II. 109 39

In situ hybridization was used to detect messenger RNA (mRNA) in a variety of rat tissues which were fixed in formalin either immediately after death or after a 24 h period of storage at 5 degrees C. A synthetic polydeoxythymidine [poly d(T)] oligonucleotide probe was used to demonstrate polyadenylated [poly (A)] mRNA in the small intestine, pancreas, liver, cerebellum, and pituitary. Of these tissues, only the liver showed a small reproducible reduction in hybridization signal following delayed fixation. Synthetic oligonucleotide probes complementary to albumin and pro-opiomelanocortin (POMC) mRNAs were hybridized to liver and pituitary, respectively. There was no significant reduction in hybridization signal in post-mortem tissues. The results suggest that some mRNAs may be remarkably stable under certain post-mortem conditions and this should encourage the wider application of in situ hybridization techniques to post-mortem material.
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PMID:In situ hybridization demonstrates the stability of mRNA in post-mortem rat tissues. 136 Apr 97

Receptor-mediated binding of leukocyte chemotactic peptide, N-formylMet-Leu-Phe (fMLP), occurs in the ciliated protozoon Tetrahymena thermophila. In vivo labelling of the cells with N-formylMet-Leu-[3H]Phe ([3H]fMLP) shows that the cells bind the ligand with high affinity (KD = 4 x 10(-9) M to 1 x 10(-8) M). Moreover, Scatchard transformations of the binding data show that there are about 5 x 10(5) binding sites per cell on the cell surface. Two fluorescent derivatives of leukocyte chemotactic peptide, N-dansylMet-Leu-Phe (dansMLP) and N-formylMet-Leu-Phe-(N-dansyl-)Lys (fMLPdanLys) compete for the N-formylMet-Leu-Phe (fMLP) binding sites on the cell surface. Moreover, both derivatives have retained significant chemoattracting potentials. Fluorescence from dansMLP, but not from fMLPdansLys and dansyl-beta-endorphin, is internalized preferentially into small vesicles. The differences may, however, reflect that the fluorescence from the dansyl group is strongly quenched by a hydrophilic microenvironment when using the two latter peptide derivatives. In contrast, the dansyl group from dansMLP must be assumed to be embedded in a hydrophobic microenvironment in the vesicular membrane or membrane protein. Rhodamine-labelled bovine serum albumin, egg albumin and cytochrome c as well as dansylated bovine serum albumin, which are poor chemoattractants, are preferentially seen to be internalized into large vesicles (food vacuoles).
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PMID:Chemotactic properties, cellular binding and uptake of peptides and peptide derivatives: studies with Tetrahymena thermophila. 147 55

Albumin binds circulating glucocorticoids such as cortisol and consequently may modify the biological activity of these steroids by altering access to target cells. Because albumin is likely present in pituitary interstitial fluid, this study was designed to compare the negative feedback effect of cortisol on pituitary adrenocorticotropic hormone (ACTH) secretion from isolated sheep pituitary cells perifused with media containing 0.25% or 2% bovine serum albumin (BSA). Pituitary cells released less (P less than 0.05) immunoreactive ACTH in response to a 10-min treatment with 10 nM ovine corticotropin-releasing hormone (oCRH) after 45 min pretreatment with 0.5 microM cortisol when media contained 2% BSA vs. 0.25% BSA. A similar enhancement in negative feedback potency was observed when cells were treated with cortisol followed by 1 nM oCRH for 60 min, with an additional 10 min co-addition of arginine vasopressin. This potentiation was not observed when a noncortisol binding protein, ovalbumin, was substituted for BSA. However, the potentiating effect of albumin was present in perifused rat pituitary cells, indicating that the effect was not species specific. We conclude that albumin enhances the negative feedback potency of cortisol in anterior pituitary corticotrophs and that the process may operate under physiological conditions to enhance cell specific delivery of this steroid to appropriate targets.
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PMID:Albumin enhances negative feedback effect of cortisol on ACTH release from sheep pituitary cells. 165 90

The results of bicycle ergometry and pharmacological tests with isoproterenol and dipyridamol, 24-hour monitoring and blood levels of endogeneous opioids were studied in 99 females with chest pain who had undergone angiography. Coronary microcirculation was examined in 29 patients by introducing albumin microspheres into the left ventricle. The angiography revealed coronary atherosclerosis in 30 patients, whereas its signs were not found in 8 females with documented coronary heart disease (CHD). The predictive value of positive exercise tests in females with angina pectoris was higher for the diagnosis of CHD, including its types without coronary atherosclerosis. In patients with cardialgias, the predictive values of exercise tests were equally low for the diagnosis of coronary atherosclerosis, vasospastic and microvascular CHD types. The patients with cardialgias caused by autonomic dyshormonal myocardiodystrophy showed low blood beta-endorphin and leu-enkephalin levels.
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PMID:[Diagnostic usefulness of ECG changes in response to exercise in women with various forms of ischemic heart disease]. 175 7

Basal levels and adrenocorticotropic hormone (ACTH)-induced increments (delta-values) of serum cortisol, dehydroepiandrosterone (DHA), dehydroepiandrosterone sulfate (DHAS), 4-androstene-3, 17-dione (A4), and 17-hydroxyprogesterone (170HP); basal testosterone (T), luteinizing hormone (LH), serum ASAT, gamma-GT, and albumin were measured in prostatic cancer patients before and after 6 months of treatment with LH-RH-agonist, with flutamide, and with LH-RH-agonist + flutamide, respectively. Basal DHA and DHAS were decreased during flutamide and LH-RH-agonist + flutamide treatment and basal A4 during treatment with LH-RH-agonist and with LH-RH-agonist + flutamide. Basal 170HP, T, and LH decreased during LH-RH-agonist and LH-RH-agonist + flutamide treatment and increased during single drug flutamide treatment. Slightly decreased delta cortisol values were observed during LH-RH-agonist and during flutamide treatment and slightly increased delta 170HP values during LH-RH-agonist and LH-RH-agonist + flutamide treatment. Values for delta DHA and delta A4 were completely unaffected by any of the treatment regimens. Elevated ASAT values were observed during treatment with flutamide and with LH-RH-agonist + flutamide. It is concluded that flutamide has no effect on the adrenal androgen response to acute ACTH stimulation.
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PMID:Flutamide has no effect on adrenal androgen response to acute ACTH stimulation in patients with prostatic cancer. 197 1

Water soluble peptides are normally not transported through the brain capillary wall, i.e. the blood-brain barrier (BBB). Chimeric peptides may be transportable through the BBB and are formed by the covalent coupling of a nontransportable peptide, e.g. beta-endorphin, to a transportable peptide vector, e.g. cationized albumin, using disulfide-based coupling reagents such as N-succinimidyl 3-[2-pyridyldithio(propionate)] (SPDP). The transcytosis of peptide into brain parenchyma, as opposed to vascular sequestration of blood-borne peptide, was quantified using an internal carotid artery perfusion/capillary depletion method. It is shown that [125I]beta-endorphin is not transported through the BBB, but is rapidly cleaved to free [125I] tyrosine via capillary peptidase. Therefore, chimeric peptide was prepared using [125I] [D-Ala2]beta-endorphin (DABE), owing to the resistance of this analogue to peptidase degradation. The [125I] DABE-cationized albumin chimeric peptide is shown to enter brain parenchyma at a rate comparable to that reported previously for unconjugated cationized albumin. When the [125I] DABE-cationized albumin chimeric peptide was incubated with rat brain homogenate at 37 C, the free [125I] DABE was liberated from the cationized albumin conjugate prior to its subsequent degradation into free [125I] tyrosine. Approximately 50% of the chimeric peptide was cleaved within 60 sec of incubation at 37 C. These studies demonstrate that 1) [125I]beta-endorphin is not transported through the BBB in its unconjugated form, 2) a [125I] DABE-cationized albumin chimeric peptide is transported through the BBB into brain parenchyma at a rate comparable to the unconjugated cationized albumin, and 3) brain contains the necessary disulfide reductases for rapid cleavage of the chimeric peptide into free beta-endorphin and this cleavage occurs before degradation of the [125I] DABE into [125I] tyrosine.
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PMID:Beta-endorphin chimeric peptides: transport through the blood-brain barrier in vivo and cleavage of disulfide linkage by brain. 213 82

Plasma levels of the N-terminal peptide of proopiomelanocortin (NPP) were measured in rainbow trout, Salmo gairdneri, following treatment of handling stress with or without administration of dexamethasone, adaptation to white and black background, and maintenance on a constant light/dark cycle. Effects of exogenously administered NPP on plasma constituents were also examined to provide insight into the biological significance of NPP. Thirty minutes of handling stress in shallow water had no effect on plasma levels of NPP during and after the stress period, whereas significant increases in plasma cortisol and glucose were observed. Intraperitoneal administration of dexamethasone blocked the stress-induced elevation of plasma levels of cortisol and caused a depression of plasma NPP. No difference was observed in plasma levels of NPP between trout adapted to a white background and those adapted to a black background. No diurnal changes in NPP were observed under an artificial light/dark cycle (14L/10D light cycle, 0500-1900 hr light) in May and September. Thus, plasma levels of NPP were considerably constant under various physiological conditions, and no synchronism was observed between plasma NPP and cortisol, although NPP modifies the corticotropin-induced release of cortisol from the interrenal. Plasma constituents such as cortisol, total protein, albumin, plasma amino nitrogen, glucose, free fatty acid, ketone body, sodium, potassium, calcium, and magnesium were not altered by intraperitoneal injections of NPP (1 or 10 micrograms) once daily for 6 days (total of six injections) or once every other day for 28 days (14 injections). High concentrations of NPP were found in the plasma 24 hr after cessation of the serial injections of NPP (10 micrograms), suggesting slow metabolic clearance of the peptide.
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PMID:Plasma profiles of the N-terminal peptide of proopiomelanocortin in the rainbow trout with reference to stress. 229 28


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