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)

Corticotropin releasing factor (CRF) is a 41-peptide amide which stimulates the release of ACTH (Vale et al. Science 1981, 213, 1394). CRF has been postulated to assume an alpha-helical conformation upon binding to its pituitary receptor (Hernandez et al. J. Med. Chem. 1993, 36, 2860). We have exploited this hypothesis in the design of a limited series of cyclic analogues and have taken into consideration the effects of side-chain deletion (Alanine scan, Kornreich et al. J. Med. Chem. 1992, 35, 1870) as well as of changes in chirality (Rivier et al. J. Med. Chem. 1993, 36, 2851), with the rationale that side chains necessary for binding could also be replaced by side-chain bridges. In particular, we have used computer modeling to predict likely side chain bridging opportunities and evaluated the effects of such replacements by correlating biological results with those derived from CD spectroscopy. We have synthesized 38 monocyclic peptide amides, competitive antagonists of human/rat CRF, using solid-phase methodology on MBHA resin. After purification by preparative RP-HPLC, the peptides were analyzed by RP-HPLC and capillary zone electrophoresis and characterized by mass spectroscopy and amino acid analysis. CRF antagonists were tested for their ability to interfere with CRF-induced release of ACTH by rat anterior pituitary cells. In most cases, one of the bridge heads was located at a position where substitution by a D-residue was tolerated (i.e., positions 12 and 20). It has become clear that careful optimization of bridge length and chirality is critical. This is best exemplified by the fact that out of the 38 analogues that were synthesized and tested, only two, [cyclo(20-23)[DPhe12,Glu20,Lys23, Nle21,38]h/rCRF12-41 and cyclo(20-23)[DPhe12,Glu20,Orn23,Nle21,38] h/rCRF12-41], were found to be more potent (3 and 2 times, respectively) than [DPhe12,Nle21,38]h/rCRF12-41, the parent compound. Six analogues belonging to two different families were found to be half as potent as the standard, 18 had 2-20% of the potency of the standard, and the others were significantly less potent. CD results of all analogues in 50% TFE (a concentration of TFE that induced nearly maximum helicity of [DPhe12,Nle21,38]h/rCRF12-41) suggest that while helicity may be an important factor for CRF analogue recognition, little correlation is found between percent helicity as determined by spectral deconvolution and biological activity in vitro.
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PMID:Conformationally restricted competitive antagonists of human/rat corticotropin-releasing factor. 818 3

A biotinylated derivative of [beta-Ala1,Lys17]-ACTH1-17-NH-(CH2)4-NH2 (ACTH1-17) was synthesized and biologically characterized. The heptadecapeptide with free N-terminus and blocked side-chains was prepared by the solid-phase method using TentaGel resin and a 4-aminobutylamide linker. Biotinyl-beta-Ala-OH was then coupled to the terminal amino group and the resulting [N alpha-(biotinyl-beta-alanyl)-beta-Ala1,Lys17]-ACTH1-17-NH-(CH2)4-N H2 (Bio-ACTH1-17) cleaved from the resin, purified and analyzed. Competition binding assays with mouse B16-F1 and human D10 and HBL melanoma cells using [125I]-alpha-MSH as radioligand gave dissociation constants for Bio-ACTH1-17 of 1.67 +/- 0.07 nM (B16-F1), 0.02 +/- 0.005 nM (D10) and 0.21 +/- 0.02 nM (HBL). The EC50 for Bio-ACTH1-17 in the B16 melanin assay was 4.15 +/- 1.0 nM. Analysis of the binding characteristics of [125I]-Bio-ACTH1-17 demonstrated that in human melanoma cells this radioligand was displaced by ACTH1-17 as well as alpha-MSH whereas in B16-F1 cells the tracer was only displaced from the binding site by ACTH1-17. Studies of Bio-ACTH1-17 with streptavidin showed that the peptide is to a large extent trapped specifically through reaction with biotin. These results demonstrate that (1) the biological characteristics of Bio-ACTH1-17 are almost identical to those of ACTH1-17, (2) Bio-ACTH1-17 is bound by avidin, and (3) Bio-ACTH1-17 may become a useful tool for MSH receptor targeting.
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PMID:Synthesis and biological properties of a biotinylated derivative of ACTH1-17 for MSH receptor studies. 838 54

Using reversed-phase HPLC in combination with a radioimmunoassay for ovine corticotropin-releasing hormone (CRH), a peptide with CRH-like immunoreactivity was isolated in pure form from an extract of the caudal spinal cord region of the spotted dogfish, Scyliorhinus canicula. The primary structure of the peptide was established as Pro-Ala-Glu-Thr-Pro-Asn-Ser-Leu10-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg- Glu-Met-Ile- Glu20-Ile-Ala-Lys-His-Glu-Asn-Gln-Gln-Met-Gln30-Ala-Asp-Ser- Asn-Arg-Arg-Ile-Met - Asp-Thr40-Ile.NH2. This amino acid sequence shows moderate structural similarity to Catostomus urotensin I (51%) and to human CRH (56%). The data provide, therefore, chemical evidence to support the conclusions of earlier immunohistochemical studies that the diffuse caudal neurosecretory system of elasmobranchs produces a peptide that is immunochemically related to teleost urotensin I peptides. However, the primary structure of urotensin I has been poorly conserved during evolution.
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PMID:A peptide from the caudal neurosecretory system of the dogfish Scyliorhinus canicula that is structurally related to urotensin I. 853 45

To investigate whether residues in the extracellular domains of melanocortin 1 receptor (MC1R) are required for ligand binding, a number of mutants were constructed where charged residues were converted to alanine. The residues targeted for mutagenesis were Ser6, Glu102, Arg109, Asp184, Glu269, and Thr272. The mutant receptor DNAs were transiently expressed in COS-1 cells and their ability to bind [N1e4,D-Phe7]-alpha-MSH (NDP-MSH) was evaluated. Substitution of Asp184 by alanine completely abolished the binding of radiolabelled NDP-MSH as well as ACTH, even though the mutated receptor could be detected on cell surface using anti MC1R specific polyclonal antiserum. Mutations of Ser6, Glu269 and Thr272 resulted in a considerable loss of affinity for radiolabelled NDP-MSH as well as the ability of alpha-MSH to displace the bound radiolabelled NDP-MSH. The results demonstrate that the extracellular loops of human MC1R contain important ligand binding epitopes.
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PMID:Identification of ligand binding residues in extracellular loops of the melanocortin 1 receptor. 860 20

An expression library was generated by partial Sau3A digestion of genomic DNA from the thermophile Bacillus thermocatenulatus and cloning of DNA fragments in pUC18 in Escherichia coli DH5alpha. Screening for lipase activity identified a 4.5 kb insert in pUC18 which directed the production of lipase in E. coli DH5alpha. A subclone with a 2.2 kb insert was sequenced. The lipase gene codes for a mature lipase of 388 amino acid residues, corresponding to a molecular weight of 43 kDa. As in other Bacillus lipases, an Ala replaces the first Gly in the conserved pentapeptide Gly-X-Ser-X-Gly found in most lipases. The region upstream of the lipase gene contains a Bacillus promoter which directs the expression of lipase in E. coli DH5alpha. The expressed lipase was isolated and purified 312-fold to homogeneity. N-terminal sequencing of the purified lipase revealed a correct cleavage of the preprotein in E. coli DH5alpha. Maximum activity was found at pH 8.0-9.0 with tributyrin and olive oil as substrates and at 60-70 degrees C with p-NPP and olive oil as substrates. The lipase showed high stability at pH 9.0-11.0 and towards various detergents and organic solvents.
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PMID:Thermoalkalophilic lipase of Bacillus thermocatenulatus. I. molecular cloning, nucleotide sequence, purification and some properties. 865 45

Group B streptococci were recently reported to possess a cell-associated collagenase. Although the enzyme hydrolyzed the synthetic collagen-like substrate N-(3-[2-furyl]acryloyl)-Leu-Gly-Pro-Ala, we found that neither the highly purified enzyme nor crude group B streptococcal cell lysate solubilized a film of reconstituted rat tail collagen, an activity regarded as obligatory for a true collagenase. We cloned and sequenced the gene for the enzyme (pepB). The deduced amino acid sequence showed 66.4% identity to the PepF oligopeptidase from Lactococcus lactis, a member of the M3 or thimet family of zinc metallopeptidases. The group B streptococcal enzyme also showed oligopeptidase activity and degraded a variety of small bioactive peptides, including bradykinin, neurotensin, and peptide fragments of substance P and adrenocorticotropin.
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PMID:Characterization of PepB, a group B streptococcal oligopeptidase. 875 83

This study was conducted to determine the binding properties of recently discovered, putative alpha-MSH antagonist 153N-6 peptide at melanocortin receptor subtypes. The results indicated that 153N-6 peptide can competitively inhibit [125I]NDP-MSH binding from all the receptor subtypes investigated. The relative potency order of 153N-6 for inhibiting [125I]NDP-MSH binding was MC1R (Ki 955 +/- 35.7 nM) = MC4R (Ki 1151 +/- 106 nM) > MC3R (Ki 3229 +/- 637 nM) > MC5R (Ki 6286 +/- 462 nM), which is different than the potency order of either NDP-MSH or alpha-MSH. Substitution of aspartic acid117 and histidine260 by alanine in melanocortin 1 receptor resulted in a 4.75-fold decrease (Ki 4541 +/- 644 nM) and an 11-fold increase (Ki 84.29 +/- 4.53 nM), respectively, in the relative potency of 153N-6 for competitively inhibiting [125I]NDP-MSH binding.
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PMID:Characterization of a putative alpha-MSH antagonist 153N-6 at melanocortin receptor subtypes by radioligand binding. 880 44

The release of catecholamines and cortisol from the perifused adrenal region and caudal vein of the eel (Anguilla rostrata) was compared with the release of 39 amino acids and related compounds. Dopamine, norepinephrine and epinephrine were present in all perifusates of the adrenal region. Dopamine release from the caudal vein exceeded that from the adrenal region, and norepinephrine and epinephrine were not detected. Cortisol was present in the perifusate of the adrenal region but virtually absent in caudal vein perifusate. Of the six substances with known or suspected neurotransmitter function, taurine, aspartate, glutamate, glycine and alanine were present in all or almost all samples from both the adrenal equivalent and the caudal vein. gamma-aminobutyric acid (GABA) was detected in a few samples from either preparation. The release of taurine and phosphoethanolamine may be linked to that of norepinephrine and epinephrine. Adrenocorticotropic hormone (ACTH) enhanced the release of cortisol, aspartate, valine, leucine and ornithine from the adrenal region, but the release appears to be from differing sources or cellular pools. Overall, the study revealed that both the adrenal region and caudal vein release a large number of amino acids and related substances. The caudal vein, and possibly other blood vessels as well, may be a major source of circulating dopamine.
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PMID:Release of amino acids and related compounds from the adrenal equivalent and caudal vein of the eel in vitro. 883 79

We have previously reported that melatonin was an effective lightening agonist in the teleost Synbranchus marmoratus, the amphibians Rana pipiens and Bufo ictericus, and in the lizard Anolis carolinensis. The hormone, previously applied to the preparations, effectively inhibited alpha-MSH darkening activity in a dose-independent manner, and was also able to reverse MSH-induced darkening. We presently describe the inhibitory effect of the indoleamine on the murine melanoma cell proliferation. Interestingly, the hormone also stimulated tyrosinase activity, with a correlated increase in melanin content. We also demonstrate that in a diverse lizard species, Urosaurus ornatus, the indoleamine was totally ineffective. The competitive MSH antagonistic activity of H-His-D-Arg-Ala-Trp-D-Phe-Lys-NH2 has been demonstrated previously in R. pipiens and U. ornatus. Herein, its inhibitory activity is also reported in another lizard species, A. carolinensis. However, this MSH analogue was inactive in S. marmoratus, and in murine melanoma cells. On the other hand, the 7 thru 10 alpha-MSH fragment, Ac-Phe-Arg-Trp-Gly-NH2, although ineffective in S. marmoratus and R. pipiens, was an alpha-MSH antagonist in A. carolinensis. Surprisingly, in the melanoma cell line, the MSH fragment exhibited no agonist or antagonist activity, but dramatically potentiated the MSH-induced increase in tyrosinase activity. These data might suggest that the fragment is participating either in the process of facilitation or in positive cooperativity. The present results, taken together with our previously reported data, demonstrate a major interspecies diversity of the MC1 subtype of melanocortin receptor, and point out the relevance of the membrane microenvironment for the final receptor configuration.
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PMID:Comparative biological activities of alpha-MSH antagonists in vertebrate pigment cells. 907 3

Examination of conformationally constrained melanotropin peptide (Ac-Nle4-c[Asp5-His-Phe7-Arg-Trp9-Ala-Lys]-NH2) on four human melanotropin receptors (hMC1R, hMC3R, hMC4R, and hMC5R) resulted in identifying the importance of ligand stereochemistry at positions 5, 7, and 9 for agonist binding affinity and receptor selectivity. A trend in ligand structure-activity relationships emerged for these peptides, with the hMC1R and hMC4R possessing similar tendencies, as did the hMC3R and hMC5R. alpha-MSH (Ac-Ser-Tyr-Ser-Met4-Glu-His-Phe7-Arg-Trp-Gly-Lys-Pro-Val-NH2), NDP-MSH (Ac-Ser-Tyr-Ser-Nle4-Glu-His-D-Phe7-Arg-Trp-Gly-Lys-Pro-Val-NH2), and MTII (Ac-Nle4-c[Asp5,D-Phe7,Lys10]-alpha-MSH(4-10)-NH2) were also examined at each of these melanocortin receptors. Interestingly, the linear NDP-MSH possessed greater binding affinity for the hMC3R and hMC5R than did the cyclic analogue MTII. The peptide Ac-Nle-c[Asp-His-Phe-Arg-D-Trp9-Ala-Lys]-NH2 demonstrated the greatest differentiation in binding affinity between the hMC1R and hMC4R (78-fold). Analogue Ac-Nle-c[Asp-His-Phe7-Arg-Trp-Ala-Lys]-NH2 resulted in micromolar binding affinity (or greater) at the hMC3R and hMC5R, demonstrating the importance of D-Phe7 for ligand binding potency at these receptors. Ac-c[Asp-His-Phe-Arg-Trp-Ala-Lys]-NH2 resulted in loss of binding affinity at the hMC5R, implicating the importance of Nle4 (or a hydrophobic residue in this position) for binding to this receptor. Ac-Nle-c[D-Asp5-His-Phe-Arg-Trp-Ala-Lys]-NH2 was unable to competitively displace [125I]NDP-MSH binding at micromolar concentrations on the hMC3R and hMC5R, suggesting the importance of chirality of Asp5 either for ligand-receptor interactions or for orientation of the side chain lactam bridge and the structural integrity of the peptide conformation. Energy calculations performed for these peptides resulted in the identification of a low-energy ligand conformer family that is common to all the ligands. The differences in ligand binding affinities observed in this study are postulated to be a result of different ligand-receptor complexed interactions and not solely to the ligand structure.
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PMID:Biological and conformational examination of stereochemical modifications using the template melanotropin peptide, Ac-Nle-c[Asp-His-Phe-Arg-Trp-Ala-Lys]-NH2, on human melanocortin receptors. 917 84


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