| 1515641 |
Antithrombotic properties of L-cysteine, N-(mercaptoacetyl)-D-Tyr-Arg-Gly-Asp-sulfoxide (G4120) in a hamster platelet-rich femoral vein thrombosis model |
None |
Blood |
Antithrombotic properties of L-cysteine, N-(mercaptoacetyl)-D-Tyr-Arg-Gly-Asp-sulfoxide (G4120) in a hamster platelet-rich femoral vein thrombosis model
Abstract
- Platelet aggregation plays an important role in the pathogenesis in arterial thrombotic disorders. The binding of fibrinogen via the Arg-Gly-Asp (RGD) recognition sequence to the platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptor is an essential step of platelet aggregation induced by various physiologic agonists, and RGD-containing peptides that bind to the GPIIb/IIIa receptor inhibit thrombus formation in vivo. L-cysteine, N-(mercaptoacetyl)D-tyrosyl-L-arginylglycyl-L alpha-aspartyl-cyclic (1----5)-sulfide, 5-oxide (G4120), a cyclic RGD-containing synthetic pentapeptide, inhibits adenosine diphosphate (ADP)-induced platelet aggregation with 50% inhibition (IC50) at a concentration of 0.05 microgram/mL in human plasma, 0.12 microgram/mL in hamster plasma, and 11 micrograms/mL in rat plasma. Corresponding values for the linear tetrapeptide Arg-Gly-Asp-Phe (RGDF) were 7 and 100 micrograms/mL in human and hamster plasma. The antithrombotic effects of G4120 and RGDF were evaluated in a hamster model consisting of a mural platelet-rich femoral vein thrombus induced by standardized endothelial cell damage. Bolus intravenous injection of G4120 was followed by a biphasic disappearance of G4120 from plasma with t1/2 alpha of 3.7 minutes and t1/2 beta of 63 minutes, corresponding to a plasma clearance of 5.2 +/- 0.68 mL/min. Bolus intravenous injection of G4120 inhibited ex vivo platelet aggregation with 0.5 mumol/L ADP and in vivo thrombus formation in a dose-dependent manner, with ID50 of 11 and 11 micrograms/kg, respectively. Bolus injection of RGDF inhibited in vivo thrombus formation; 43% inhibition was obtained at a dose of 30 mg/kg. Thus, this hamster platelet-rich femoral vein thrombosis model may be useful for the investigation of the antithrombotic properties of platelet GPIIb/IIIa antagonistic peptides. The cyclic synthetic peptide G4120 appears to have a very potent antithrombotic activity in vivo.
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| 1517012 |
Cyclo(L-prolyl-L-N-methylphenylalanyl). Conformation in solution and in the crystal |
10.1111/j.1399-3011.1992.tb00781.x. |
Int J Pept Protein Res |
Cyclo(L-prolyl-L-N-methylphenylalanyl). Conformation in solution and in the crystal
Abstract
- Detailed analysis of the proton and carbon-13 NMR spectra of cyclo(L-prolyl-L-N-methylphenylalanyl) in chloroform and methanol in relation to its nonmethylated analog provided information on the conformation of the title compound in solution as well as on the effect of N-methylation and solvation. The X-ray structure of the title compound in the crystalline state showed the same conformational features as the solution structure. The phenyl group folds over the diketopiperazine ring which resembles a flattened half-chair. Both amide bonds are considerably nonplanar. The pyrrolidine ring of proline shows a strong pucker at the ring junction with the largest chi 5 value hitherto observed.
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| 1520265 |
Isolation of a novel protein from the outer layer of the vitelline membrane |
10.1042/bj2860017. |
Biochem J |
Isolation of a novel protein from the outer layer of the vitelline membrane
Abstract
- The outer layer of the vitelline membrane from hen egg yolk consists of ovomucin, vitelline membrane outer layer protein I (VMOI) and lysozyme. Here we report the occurrence of a further basic protein (pI 11.5) in the outer layer, which was designated as vitelline membrane outer layer protein II (VMOII). It was dissociated from the outer layer in a 10% (w/v) NaCl solution and purified to homogeneity by ion-exchange chromatography. VMOII is a simple protein with a molecular mass of 6000 Da, as determined by sedimentation equilibrium analysis. The amino acid composition of VMOII was characterized by the absence of Met and high contents of cystine (half) (14%) and basic amino acids (6% Arg, 6% Lys and 3% His). Analysis of carboxymethylated VMOII indicated that all cysteine residues were involved in disulphide bonding, which appears to facilitate the binding of SDS to the protein. Sequence comparison of the N-terminal 20 residues revealed no identity with other known proteins. VMOII contained a small amount of alpha-helix and was quite resistant to heat denaturation.
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| 1521179 |
Conopressin G, a molluscan vasopressin-like peptide, alters gill behaviors in Aplysia |
10.1139/y92-032. |
Can J Physiol Pharmacol |
Conopressin G, a molluscan vasopressin-like peptide, alters gill behaviors in Aplysia
Abstract
- Superfusion of an invertebrate vasopressin structural analogue, conopressin G, over the abdominal ganglion of an in vitro preparation of Aplysia californica has significant neurophysiological and behavioral effects. Both the amplitude of the siphon-evoked gill withdrawal reflux and concomitant activity in gill motor neurons are reduced in the presence of conopressin G. Moreover, the frequency of spontaneous gill movements and their neural correlate, interneuron II activity, are increased. These behavioral modifications strongly resemble those that occur during the food-aroused behavioral state in intact Aplysia. In addition, conopressin G superfusion reduces both the excitability of gill motor neurons and the strength of gill contractions in response to gill motor neuron discharges elicited by direct depolarizing current. A role for conopressin G or a similar peptide in the modulation of gill behaviors associated with the food-aroused state is suggested.
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| 1523158 |
A vasotocin-like peptide in Aplysia kurodai ganglia: HPLC and RIA evidence for its identity with Lys-conopressin G |
10.1016/0196-9781(92)90069-f. |
Peptides |
A vasotocin-like peptide in Aplysia kurodai ganglia: HPLC and RIA evidence for its identity with Lys-conopressin G
Abstract
- The presence of a vasopressin (VP)- or vasotocin (VT)-like peptide in the central nervous system of the gastropod mollusc Aplysia has been indicated previously. In the case of Aplysia californica, HPLC and RIA evidence suggested the peptide was VT-like but not identical with the nonmammalian vertebrate peptide Arg8VT (AVT). In the present study, anterior ganglia extracts from the related species Aplysia kurodai were analyzed by HPLC followed by RIA. Further analysis of the major AVT-IR peak showed it to be indistinguishable, in three distinct solvent systems, from the sea snail venom peptide Lys-conopressin G, but to be different from the vertebrate peptides Arg8VP (AVP), Lys8VP (LVP), AVT, oxytocin (OT), mesotocin, isotocin, aspargtocin, glumitocin, and valitocin, from the sea snail venom peptide Arg-conopressin S, and from the peptides Lys8VT and Gln8OT. In addition, the carboxymethylated (CM) A. kurodai peptide had the same HPLC retention time as CM-Lys-conopressin G. The HPLC/RIA results suggest that (i) based on the properties of the solvent systems used, the A. kurodai peptide has two basic amino acids (like the conopressins but unlike the vertebrate peptides), and (ii) there is a high probability that the A. kurodai peptide is identical with Lys-conopressin G.
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| 1525934 |
Solution forms of an antitumor cyclic hexapeptide, RA-VII in dimethyl sulfoxide-d6 from nuclear magnetic resonance studies |
10.1248/cpb.40.1050. |
Chem Pharm Bull (Tokyo) |
Solution forms of an antitumor cyclic hexapeptide, RA-VII in dimethyl sulfoxide-d6 from nuclear magnetic resonance studies
Abstract
- Using high-resolution proton nuclear magnetic resonance (1H-NMR) and carbon-13 nuclear magnetic resonance (13C-NMR) experiments, we have assigned three discernible configurational isomers observed in dimethyl sulfoxide-d6 (DMSO-d6) for an antitumor cyclic hexapeptide, RA-VII isolated from Rubia cordifolia. The largest isomer, amounting to 64%, has been assigned as conformer A with only a cis configuration between Tyr-5 and Tyr-6. The second configurational isomer, accounting for 32%, has adopted cis configurations between both Tyr-5 and Tyr-6 and between Ala-2 and Tyr-3. The third isomer, amounting to 4%, was determined to have cis configurations for all of the three N-methyl amide bonds.
|
| 1530630 |
Binding selectivity of rhizoxin, phomopsin A, vinblastine, and ansamitocin P-3 to fungal tubulins: differential interactions of these antimitotic agents with brain and fungal tubulins |
10.1016/0006-291x(92)91255-o. |
Biochem Biophys Res Commun |
Binding selectivity of rhizoxin, phomopsin A, vinblastine, and ansamitocin P-3 to fungal tubulins: differential interactions of these antimitotic agents with brain and fungal tubulins
Abstract
- The binding of four potent antimitotic agents, rhizoxin (RZX), phomopsin A (PMS-A), ansamitocin P-3 (ASMP-3), and vinblastine (VLB), to tubulins from RZX-sensitive and -resistant strains of Aspergillus nidulans, Schizosaccharomyces pombe, and Saccharomyces cerevisiae was investigated. Mycelial extracts to which RZX could bind contained beta-tubulin with Asn as the 100th amino acid residue (Asn-100) in all cases, and those without affinity for RZX contained beta-tubulins with either Ile-100 or Val-100. Though PMS-A shares the same binding site as RZX and ASMP-3 on porcine brain tubulin (Asn-100), only ASMP-3 bound Asn-100 fungal tubulins in a competitive manner with respect to RZX. PMS-A and VLB, which strongly bind to porcine brain tubulin, did not bind to any of the fungal mycelial extracts examined. The results indicate differential interactions of these antimitotic agents with brain and fungal tubulins.
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| 1538058 |
Age-related alterations in actin cytoskeleton and receptor expression in human leukocytes |
10.1093/geronj/47.2.b37. |
J Gerontol |
Age-related alterations in actin cytoskeleton and receptor expression in human leukocytes
Abstract
- We studied a number of parameters, which may all depend upon cytoskeletal function, comparing lymphocytes and granulocytes (PMN) from young and old healthy donors. F-actin content was measured by NBD-phallacidin staining, followed by flow cytometry and was expressed as mean channel fluorescence (MCF). There were no differences in the basal F-actin content of PMN obtained from young (under 35 years old) and old donors (above 65 years). In contrast, the basal F-actin content was higher in lymphocytes obtained from the old donors (MCF, 56.8 +/- 2.9 vs 48.1 +/- 2.6 in the young; mean +/- SEM, n = 20, p less than .03). Stimulus-induced actin polymerization was slightly lower in the older age-group both in PMN and lymphocytes, but a significant difference was found only in PMN stimulated with the chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (MCF 97.9 +/- 4.7 vs 88.6 +/- 3.4; young vs old, mean +/- SEM, n = 20, p less than .05). Interleukin-2 receptor expression was measured by staining with FITC-conjugated anti-CD25 antibodies and flow cytometry, following stimulation with phytohemagglutinin (PHA) or pokeweed mitogen (PWM). Perturbation of the cytoskeletal system with pentoxifylline, which has been shown to decrease F-actin content and inhibit the expression of several cell surface receptors, had similar effects on leukocytes from young and old donors.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 1548227 |
A novel extracellular cyclic lipopeptide which promotes flagellum-dependent and -independent spreading growth of Serratia marcescens |
10.1128/jb.174.6.1769-1776.1992. |
J Bacteriol |
A novel extracellular cyclic lipopeptide which promotes flagellum-dependent and -independent spreading growth of Serratia marcescens
Abstract
- Serrawettin W2, a surface-active exolipid produced by nonpigmented Serratia marcescens NS 25, was examined for its chemical structure and physiological functions. The chemical structure was determined by degradation analyses, infrared spectroscopy, mass spectrometry, and proton magnetic resonance spectroscopy. Serrawettin W2 was shown to be a novel cyclodepsipeptide containing a fatty acid (3-hydroxydecanoic acid) and five amino acids. The peptide was proposed to be D-leucine (N-bonded to the carboxylate of the fatty acid)-L-serine-L-threonine-D-phenylalanine-L-isoleucine (bonded to the 3-hydroxyl group). By examining the effects of isolated serrawettin W2 on serrawettinless mutants, this lipopeptide was shown to be active in the promotion of flagellum-independent spreading growth of the bacteria on a hard agar surface. The parent strain NS 25 formed a giant colony with a self-similar characteristic after incubation for a relatively long time (1 to 2 weeks), similar to other fractal colony-producing strains of S. marcescens (producers of the different serrawettins W1 and W3). On a semisolid medium that permitted flagellum-dependent spreading growth, an external supply of serrawettin W2 accelerated surface translocation of a serrawettinless mutant during a short period (12 h) of observation. In contrast, bacterial translocation in the subsurface space of the semisolid agar was not enhanced by serrawettins. Thus, the extracellular lipids seem to contribute specifically to the surface translocation of the bacteria by exhibiting surfactant activity.
|
| 1563582 |
Detection of mutations in the insulin receptor gene in patients with insulin resistance by analysis of single-stranded conformational polymorphisms |
10.1007/BF00400927. |
Diabetologia |
Detection of mutations in the insulin receptor gene in patients with insulin resistance by analysis of single-stranded conformational polymorphisms
Abstract
- We analyzed single-stranded conformational polymorphisms to screen for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Using this new technique, we demonstrated the existence of mutations in the insulin receptor gene which we had identified previously. In addition, a new mutation was found in exon 20 of the insulin receptor gene in a patient with moderate insulin resistance associated with morbid obesity, acanthosis nigricans, and polycystic ovary syndrome. The patient was heterozygous for a mutation substituting Leu (CTG) for Pro (CCG) at codon 1178. Pro1178 is a part of a characteristic sequence motif (D1150 F1151 G1152---A1177 P1178 E1179) common to many protein kinases. Analysis of single-stranded conformational polymorphisms was also used to estimate the frequency of a polymorphism at codon 1058. The two codons CAC (1058 His) and CAT (1058 His) both had a prevalence of 50% in 30 Japanese subjects. These data demonstrate that analysis of single-stranded conformational polymorphisms is a simple and sensitive screening method for mutations and polymorphisms in the insulin receptor gene in subjects with or without insulin resistance. Identification of a mutation in the insulin receptor gene in a patient with a moderate degree of insulin resistance associated with morbid obesity suggests that insulin receptor mutations may exist in patients with Type 2 (non-insulin-dependent) diabetes mellitus associated with a moderate degree of insulin resistance.
|
| 1575686 |
Solution structures of nisin A and its two major degradation products determined by n.m.r |
10.1042/bj2830413. |
Biochem J |
Solution structures of nisin A and its two major degradation products determined by n.m.r
Abstract
- The conformations of nisin and two major degradation products, nisin-(1-32)-peptide (nisin1-32) and des-delta Ala5-nisin1-32 (where delta Ala is alpha beta-didehydroalanine), in aqueous solution have been determined from n.m.r. data. Sequential assignments of the peptides using correlation spectroscopy ('COSY'), homonuclear Hartmann-Hahn spectroscopy ('HOHAHA'), nuclear Overhauser enhancement spectroscopy (NOESY), relayed NOESY and rotating-frame nuclear Overhauser spectroscopy (ROESY) experiments are presented, including stereospecific assignments of beta-methylene protons of the lanthionine residues. ROESY experiments are also used to detect flexible regions in the polypeptide chain. A dynamic-stimulated-annealing approach is used for structural determination. It can be concluded that all these peptides are flexible in aqueous solution, with no experimental evidence of preferred overall conformations; the only defined conformational features are imposed by the presence of the lanthionine residues. Low-temperature studies also reveal that des-delta Ala5-nisin1-32 adopts conformations similar to those when the ring is intact, suggesting that the loss of activity of this degradation product is due to the absence of the delta Ala5 residue rather than to the conformational consequences of ring-opening."
|
| 1578481 |
Structure-activity studies of a novel bicyclic oxytocin antagonist |
10.1021/jm00087a009. |
J Med Chem |
Structure-activity studies of a novel bicyclic oxytocin antagonist
Abstract
- In this report, we describe structure-activity studies of the bicyclic oxytocin antagonist Mpa1,cyclo(Glu4,Lys8)oxytocin. The monocylic analogue dPen1, (Glu4,Lys8)oxytocin was a weak oxytocin antagonist with a pA2 value of 5.8 in the uterotonic assay. Bicyclization of this analogue yielded dPen1,cyclo(Glu4,Lys8)oxytocin, a potent antagonist of oxytocin in the uterotonic assay (pA2 8.74) with a potency 3 times greater than that of Mpa1,cyclo(Glu4,Lys8)oxytocin. dPen1,cyclo(Glu4,Lys8)oxytocin also was a weak antagonist in the pressor assay with a pA2 of 6.3. To establish if the potent antagonistic effects of these bicyclic compounds was because of the lactam ring or merely the result of obtaining an optimal degree of lipophilicity of the side chains in positions 4 and 8, we synthesized a series of analogues containing neutral and/or charged groups on these side chains. Monocyclic derivatives of Mpa1,Gln4,Lys(CHO)8oxytocin were moderate to weak agonists of oxytocin all following classical structure-activity profiles of oxytocin. The monocyclic derivatives of dPen1,Gln4,Lys(CHO)8oxytocin were antagonists of oxytocin which was attributed to the dPen1 substitution. However, the potency of all of these latter derivatives was at least 1 order of magnitude less than dPen1,cyclo(Glu4,Lys8)oxytocin. These results suggest that the potent antagonistic properties of the bicyclic analogues Mpa1,cyclo(Glu4,Lys8)oxytocin and dPen1,cyclo(Glu4,Lys8)oxytocin can be attributed to the effect of the lactam bridge on the conformational flexibility and topographical properties of the analogues, rendering them more favorable for binding to the receptor in such a manner as to prevent transduction of a biological response.
|
| 1591281 |
Sequencing of cyclodepsipeptides (destruxins) using positive fast atom bombardment desorption tandem mass spectrometry |
10.1002/bms.1200210108. |
Biol Mass Spectrom |
Sequencing of cyclodepsipeptides (destruxins) using positive fast atom bombardment desorption tandem mass spectrometry
Abstract
- The development of fast atom bombardment tandem mass spectrometry methodology is applied to the sequencing of the destruxin toxins (cyclodepsipeptides) which are 'wrong' cyclopeptides. The strategy is discussed in detail. Possible ways to overcome problems related to the resolution of isobaric fragment ions using deuterated compounds and the distinction between sequence and retrosequence are examined."
|
| 1591397 |
Desorption of ions from locust tissues. II. Metabolites of E-destruxin using negative-ion fast-atom bombardment mass spectrometry |
10.1002/rcm.1290060107. |
Rapid Commun Mass Spectrom |
Desorption of ions from locust tissues. II. Metabolites of E-destruxin using negative-ion fast-atom bombardment mass spectrometry
Abstract
|
| 1597855 |
Cyclic RGD peptide analogues as antiplatelet antithrombotics |
10.1021/jm00089a014. |
J Med Chem |
Cyclic RGD peptide analogues as antiplatelet antithrombotics
Abstract
- Stimulation of platelets activates GPIIbIIIa, the heterodimeric integrin receptor, to bind fibrinogen (Fg), which results in platelet aggregation. GPIIbIIIa/Fg binding inhibitors are potentially suitable for acute use during and after thrombolytic therapy as antithrombotic agents. Incorporation of the tripeptide sequence Arg-Gly-Asp (RGD), a common structural element of many integrin ligands, into cyclic peptides produced a series of peptides of the general structure BrAc-(AA1)-RGD-Cys-OH, which were prepared by solid-phase peptide synthesis. Cyclization was accomplished by reaction of the N-terminal bromoacetyl group with the cysteine sulfhydryl at pH 8 at high dilution, resulting in thioether-bridged cyclic peptides cyclo-S-Ac-(AA1)-RGD-Cys-OH. Use of alpha-substituted bromoacetyl groups gave rise to an analogous series of acetyl-substituted thioether-bridged cyclic peptides. Oxidation of the thioethers produced separable diastereomeric sulfoxide-bridged cyclic peptides. After thorough evaluation in a GPIIbIIIa ELISA assay and a platelet aggregation assay, G-4120 (70A; AA1 = D-Tyr; sulfoxide bridge) was selected for further investigation as an antithrombotic agent. G-4120 was equipotent in the platelet aggregation assay to kistrin, a highly potent inhibitor of fibrinogen-mediated platelet aggregation isolated from snake venom (IC50 = 0.15 microM).
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