[Effect of sialic acid on hemolysis of the paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes].
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Complement C3b↗
Biomedical subjects
C H Li
Publications and source records attributed to C H Li.
Preparation and properties of tritiated human [Tyr18, Trp27]-beta-endorphin.
Tritiated [Tyr18, Trp27]-beta h-EP was prepared from the corresponding diiodotyrosine derivative by catalytic reduction in the presence of carrier free tritium gas. A photoaffinity probe for beta-endorphin (beta-EP) receptors was prepared by selective modification of [Tyr18, Trp27]-beta h-endorphin with 2-nitro-4-azidophenylsulfenyl chloride (2,4-NAPS-C1) under acidic conditions to yield [Trp18-2,4-NAPS-Trp27]-beta h-endorphin (NAPS-beta-EP). NAPS-beta-EP was purified by high performance liquid chromatography and characterized by ultraviolet absorption spectroscopy and peptide mapping. Tritiated NAPS-beta-EP was prepared from tritiated [Tyr18, Trp27]-beta h-endorphin with 2,4-NAPS-C1. The ability of NAPS-beta-EP to form covalent bonds to macromolecules due to photolysis was established using bovine serum albumin. The efficiency of photolytic cross-linking was 15% and the equilibrium dissociation constant was 1.3 X 10(-5) M.
Affinity Labels↗
[Studies on the fate of artesunate by GC-MS, HPLC and TLCS methods].
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Animals↗
Conformational comparison of human pituitary growth hormone and human chorionic somatomammotropin (human placental lactogen) by second-order absorption spectroscopy.
Second-order absorption spectra strongly suggest the presence of a hydrogen bond between the single Trp of human pituitary growth hormone (hGH) and a carboxylate ion. This hydrogen-bonded complex is buried within the hydrophobic interior of the hGH molecule. Although the homologous Trp in human chorionic somatomammotropin [human placental lactogen, HCS(hPL)] is also buried within the hydrophobic interior of the molecule, there is no evidence that it is hydrogen bonded in the native protein. However, during the early stages of thermolysin digestion of HCS(hPL), both difference and second-order absorption spectra do indicate the transient presence of a similar hydrogen-bonded Trp-carboxylate complex. The molar extinction coefficients of hGH and HCS(hPL) have been refined.
Growth Hormone↗
beta-Endorphin: evidence for the existence of opioid and non-opioid binding components for the tritiated human hormone in NG108-15 cells.
Human beta-endorphin (beta h-EP) binding on neuroblastoma X glioma hybrid NG108-15 cells using tritiated human beta endorphin (3H-beta h-EP) as a primary ligand was found to have a component which was not displacable with [D-Ser2 )-Leu-enkephalin-Thr6 (DSLET). The beta h-EP binding on these cells after saturation of the delta opiate sites with 200 nM DSLET was further characterized with synthetic beta h-EP analogs. The nonopioid binding site appears to recognize beta h-EP-(6-31), beta h-EP-(21-31) and beta h-EP-(28-31). Under these conditions, these COOH-terminal segments fully displace the tritiated beta h-EP. However, beta h-EP-(1-27) does not further displace 3H-beta h-EP in the presence of DSLET. The fact that a combination of DSLET and beta h-EP-(6-31) results in a full displacement of 3H-beta h-EP provides direct evidence for the existence of two binding sites for beta h-EP in NG108-15 cells, one recognizing the NH2-terminal enkephalin sequence and the other the non-opioid COOH-terminal segment.
Binding, Competitive↗
Beta-endorphin: demonstration of binding sites in three human neuroblastoma cell lines specific for the COOH-terminal segment of the human hormone.
This communication reports for the first time specific binding sites in human neuroblastoma cells for human beta-endorphin (beta h-EP). Three cell lines (IMR-32, NMB and Kelly) were investigated and found to bind tritiated beta h-EP with an apparent dissociation constant of 2.2-4.2 nM. Further characterization with camel beta-EP and synthetic analogs indicated that the binding is most likely mediated by the COOH-terminal segments. beta h-EP-(6-31) had significant potency (15-75%) and beta h-EP-(1-27) was without displacing activity. The camel beta-EP has below 1% of the human beta-EP activity.
Binding, Competitive↗
Effects of beta-endorphin fragment 6-31 on morphine- and beta-endorphin-induced growth hormone and prolactin release.
A fragment of human beta-endorphin (beta h-EP-(6-31] has been proposed as an endogenous inhibitor of beta-endorphin. We have evaluated the effects of the fragment on beta-endorphin- and morphine-induced prolactin and growth hormone release. It inhibited both morphine- and beta-endorphin-induced prolactin release, while it was ineffective on the release of growth hormone.
Animals↗
Isolation, structure, and synthesis of a human seminal plasma peptide with inhibin-like activity.
A basic peptide isolated from pooled human seminal plasma exhibited inhibin-like activity by suppressing pituitary follicle-stimulating hormone secretion in vitro and in vivo. The peptide has been characterized and sequenced, and a 31-amino-acid synthetic replicate showed full biological activity in vitro.
Amino Acid Sequence↗
Detection of bovine pancreatic trypsin inhibitor (bPTI) in bovine and ovine pituitaries, bovine brain, and adrenal medulla. A specific radioimmunoassay for bPTI.
An antiserum against bovine pancreatic trypsin inhibitor (bPTI) has been raised in rabbits. The antiserum does not cross-react with known pituitary hormones and other proteins. A specific radioimmunoassay for bPTI has been developed. The ED50 is about 250 fmol per assay tube and the sensitivity is reliable to 15 fmol per tube. Immunoreactivity could be detected in bovine and sheep pituitaries, bovine brain, and adrenal medulla, but not in human, pig, and rat pituitaries. In the bovine pituitary the immunoreactivity is restricted to the posterior lobe.
Adrenal Medulla↗
beta-Endorphin-induced analgesia is inhibited by synthetic analogs of beta-endorphin.
Competitive antagonism of human beta-endorphin (beta h-EP)-induced analgesia by synthetic beta h-EP analogs with high in vitro opiate receptor binding to in vivo analgesic potency ratio has been demonstrated. A parallel shift of the dose-response curve for analgesia to the right was observed when either beta h-EP or [ Trp27 ] -beta h-EP was coinjected with various doses of [Gln8, Gly31 ]-beta h-EP-Gly-Gly-NH2, [Arg9,19,24,28,29]-beta h-EP, or [ Cys11 ,26, Phe27 , Gly31 ]-beta h-EP. It was estimated that the most potent antagonist, [Gln8, Gly31 ]-beta h-EP-Gly-NH2, is at least 200 times more potent than naloxone.
Analgesia↗
Synthesis and biological activity of human inhibin-like peptide-(1-31).
A peptide containing 31 amino acids with inhibin-like activity has been synthesized by the solid-phase method. The synthetic product was shown to be homogeneous in high-performance liquid chromatography and paper electrophoresis. In the mouse pituitary incubation system, the follitropin-suppressing activity of the synthetic peptide was comparable to that of the natural product. It was also active in suppressing lutropin-releasing hormone-induced follitropin release in vivo in immature male rats.
Animals↗
Synthetic somatomedin C: comparison with natural hormone isolated from human plasma.
The biological and immunological properties of a chemically synthesized preparation of somatomedin C (Sm-C) were compared with those of the natural product isolated from human plasma. The two preparations produced identical curves in the radioimmunoassay and radioreceptor assay for Sm-C and in the radioreceptor assay for insulin. They were identical in their ability to stimulate DNA synthesis in confluent BALB/c 3T3 cells previously exposed to platelet-derived growth factor, and the biological activities of both preparations were completely neutralized by a monoclonal antibody raised against native Sm-C. These studies demonstrate that the chemically synthesized product is equivalent to the native molecule in all important respects and that it can be used interchangeably with the natural product for any studies that are contemplated.
Animals↗
beta-endorphin-(1-27) is an antagonist of beta-endorphin analgesia.
beta h-Endorphin-(1-27), a naturally occurring fragment of human beta-endorphin (beta h-endorphin), diminishes the analgesic effect of beta h-endorphin when coinjected intra-cerebroventricularly into mice. A parallel shift in the dose-response curve of beta h-endorphin in the presence of beta h-endorphin-(1-27) suggests competition at the same site. The potency of beta h-endorphin-(1-27) in antagonizing analgesia is greater than 4 times greater than that of the opiate antagonist naloxone.
Analgesia↗
beta-Endorphin: characterization of binding sites specific for the human hormone in human glioblastoma SF126 cells.
The established human glioblastoma cell line SF126 was found to bind tritiated human beta-endorphin (beta h-EP) in a saturable fashion. From displacement studies, the ED50 was estimated to be about 2.5 nM. The Kd was estimated as 1.9 X 10(-9) M and Scatchard analysis showed a biphasic pattern with a predominant low-affinity component. Binding reached a maximum at about 90 min at 22 degrees C and was instantaneously reversible. Tritiated [D-Ala2,D-Leu5]enkephalin and tritiated dihydromorphine did not bind to the cells. Sodium at a concentration of 150 mM decreased the specific binding by 80%. The interaction with the cellular binding site appeared to be mediated by the COOH-terminal segment of beta h-EP, as beta h-EP-(6-31) retained a high potency for displacing tritiated beta h-EP, and beta h-EP-(1-27) has no activity. Camel beta-EP was only about 1% as active as the human hormone.
Binding, Competitive↗
Synthesis of shrimp red pigment-concentrating hormone analogs and their biological activity in locusts.
Two analogs of the red pigment-concentrating hormone (RPCH) have been synthesized by the solid-phase method: [Thr6]-RPCH (I) and [Tyr4, Thr6]-RCPH (II). Analog I has the same amino acid composition as the second adipokinetic hormone (AKH-II) isolated from locust corpora cardiaca. Bioassay for lipid-mobilizing activity in adult male locusts gave the following increases in hemolymph lipid content: AKH-I, 3.5; I, 2.4; II, 2.9. The biological response shown by I lends support to the conclusion that its sequence is that of the presumptive AKH-II. Replacement of Phe in position 4 by Tyr does not reduce the adipokinetic response.
Animals↗
Adrenocorticotropin. 57. Synthesis and biological activity of ostrich and turkey hormones.
Synthesis of ostrich and turkey corticotropin (ACTH) has been accomplished by the solid-phase method. Each was identical to the natural hormone in high performance liquid chromatography. Relative potencies in a lipolytic assay in isolated rabbit fat cells were: human ACTH, 100; ostrich ACTH, 53; turkey ACTH, 28. In isolated rat fat cells relative lipolytic potencies were: human ACTH, 100; ostrich ACTH, 2; turkey ACTH, 13. It was concluded that lipolytic potency is sensitive to alterations in structure throughout the entire length of the ACTH sequence in the rat fat cell assay.
Adipose Tissue↗
Synthesis of human pancreatic growth hormone-releasing factor and two omission analogs by segment-coupling method in aqueous solution.
The human growth hormone-releasing factor (GRF) peptides [GlyS15]-GRF-(1-15) (IV), trifluoroacetyl-GRF-(20-44) (VI), trifluoroacetyl-GRF-(18-44) (VIII), and trifluoroacetyl-GRF-(16-44) (X) were synthesized by the solid-phase method. Each of the peptides was reacted with citraconic anhydride and the trifluoroacetyl group was removed by reaction with 10% hydrazine in water. The citraconylated GRF-(1-15) peptide was coupled to the (20-44), (18-44) or (16-44) peptides by reaction with silver nitrate/N-hydroxysuccinimide to give GRF-(1-15)-(20-44) (XII), GRF-(1-15)-(18-44) (XIII), or GRF-(1-44), respectively. GRF-(1-44) was shown to stimulate the release of rat growth hormone from rat pituitary cells with an ED50 = 8.8 X 10(-11)M. Peptides XII and XIII were inactive, either as agonists or as antagonists of the action of GRF-(1-44).
Animals↗
Insulin-like growth factor I/somatomedin C (IGF-I/Sm C): comparison of natural, solid phase synthetic and recombinant DNA analog peptides in two radioligand assays.
Investigation of the biologic activity of Insulin-like Growth Factor I/Somatomedin C (IGF-I/Sm C) has been hampered by the scarcity of purified material. The synthesis of this molecule by the solid phase procedure and an analog of IGF-I/Sm C by recombinant DNA technology offers promise that studies of the biologic activity of IGF-I/Sm C will soon be possible. We have found that natural IGF-I/Sm C and the two synthetic peptides behave similarly in two radioligand systems, providing evidence that these molecules possess the requisite structural integrity for use in such biological studies.
Humans↗