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G Lindeberg

Publications and source records attributed to G Lindeberg.

At least 37 records · Page 2Linked to original sources
PubMed1991

Purification of synthetic peptides. Immobilized metal ion affinity chromatography (IMAC).

Immobilized metal ion affinity chromatography (IMAC) is a useful method for purification of synthetic peptides with an N-terminal metal-binding amino acid such as His, Trp, or Cys, especially when such residues are not present in other parts of the molecule. In solid phase peptide synthesis (SPPS), capping with acetic anhydride will, in principle, produce truncated peptides as the only side-products due to incomplete couplings. Consequently, only the desired product will carry the affinity label. Most of the impurities, therefore, can be removed by a single passage through an IMAC column. Some representative examples are presented, where fairly large peptides (30-40 amino acid residues) were efficiently purified by this approach.

Amino Acid Sequence↗
PubMed1988

The solution conformation of the antibacterial peptide cecropin A: a nuclear magnetic resonance and dynamical simulated annealing study.

The solution conformation of the antibacterial polypeptide cecropin A from the Cecropia moth is investigated by nuclear magnetic resonance (NMR) spectroscopy under conditions where it adopts a fully ordered structure, as judged by previous circular dichroism studies [Steiner, H. (1982) FEBS Lett. 137, 283-287], namely, 15% (v/v) hexafluoroisopropyl alcohol. By use of a combination of two-dimensional NMR techniques the 1H NMR spectrum of cecropin A is completely assigned. A set of 243 approximate interproton distance restraints is derived from nuclear Overhauser enhancement (NOE) measurements. These, together with 32 distance restraints for the 16 intrahelical hydrogen bonds identified on the basis of the pattern of short-range NOEs, form the basis of a three-dimensional structure determination by dynamical simulated annealing [Nilges, M., Clore, G.M., & Gronenborn, A.M. (1988) FEBS Lett. 229, 317-324]. The calculations are carried out starting from three initial structures, an alpha-helix, an extended beta-strand, and a mixed alpha/beta structure. Seven independent structures are computed from each starting structure by using different random number seeds for the assignments of the initial velocities. All 21 calculated structures satisfy the experimental restraints, display very small deviations from idealized covalent geometry, and possess good nonbonded contacts. Analysis of the 21 converged structure indicates that there are two helical regions extending from residues 5 to 21 and from residues 24 to 37 which are very well defined in terms of both atomic root mean square differences and backbone torsion angles. For the two helical regions individually the average backbone rms difference between all pairs of structures is approximately 1 A. The long axes of the two helices lie in two planes, which are at an angle of 70-100 degrees to each other. The orientation of the helices within these planes, however, cannot be determined due to the paucity of NOEs between the two helices.

Anti-Bacterial Agents↗
PubMed1983

Structural requirements for microvascular permeability-increasing ability of peptides. Studies on analogues of a fibrinogen pentapeptide fragment.

A pentapeptide, Ala-Arg-Pro-Ala-Lys, liberated from fibrinogen during plasmin-mediated fibrinolysis, was shown earlier to increase microvascular permeability in rat and human skin. Eighteen new analogues have now been synthesized in addition to the 15 previously prepared and examined for their effect on permeability. The old concept that a tetrapeptide with basic amino acids at both ends and a proline residue adjacent to the N-terminal amino acid is essential for high activity on permeability, has now been challenged. The results obtained with several of the new analogues strengthen this concept. More interestingly, however, the third amino acid, which was found in earlier studies to be less sensitive to exchange, has now been deleted as well as duplicated with only a modest loss of activity of the peptide. The chirality of the C-terminal amino acid, most surprisingly, does not seem to be crucial for peptide activity. Slightly superpotent analogues were obtained on amidation of the C-terminus. In addition, a few naturally occurring peptides, namely tuftsin, substance P, neurotensin and bradykinin, the amino acid sequences of which all exhibit characteristic features of some of our active peptide analogues were investigated in the same test system. Tuftsin displayed a potency equal to that of the pentapeptide. The other three peptides were all highly superpotent in this assay system.

Animals↗
PubMed1981

Des-tyrosine1-gamma-endorphin increases the antinociceptive efficacy of morphine in the rat.

Repeated injections of des-tyrosine1-gamma-endorphin (DT gamma E) to rats subjectively increased sensitivity to handling. After 8 days of treatment, the animals were supersensitive to a low dose of morphine in the foot-shock test. Acute treatment with DT gamma E gave no significant increase in morphine sensitivity. The results indicate that DTgammaE given chronically interacts with opioid receptor-effector mechanisms.

Analgesia↗
PubMed1981

Inhibitory effect of O-alkylated analogues of oxytocin and vasopressin on human and rat myometrial activity.

Analogues of oxytocin and vasopressin modified through O-alkylation (methyl, ethyl and butyl) at position 2 of the peptide chain were synthesized and tested for effects on the rat uterus in vivo and on isolated rat and human myometrial preparations. None of the analogues showed any appreciable oxytocic activity. When tested together with oxytocin or vasopressin the analogues inhibited the uterine response to the hormones in a dose-dependent and reversible way. Ethyl-analogues were more powerful antagonists than methyl-analogues but further prolongation of the alkyl-chain (butyl) diminished the antagonistic properties of the compounds. The effect of antagonistic potency of deamination at position 1 of the analogues varied among the analogues and depended on the test system used. The possible clinical value of the antagonists is discussed.

Animals↗
PubMed1980

Antidiuretic agonism and antagonism of some O-alkylated analogues of vasopressin containing 2-O-alkylated tyrosine.

A series of 2-O-alkylated tyrosine analogues of lysine-vasopressin and desamino-lysine and arginine-vasopressin were synthesized and tested for antidiuretic activity in the water-loaded anaesthetized rat. The analogues displayed only weak antidiuretic activities. When they were infused in the rats together with lysine vasopressin it was found that 1-deamino-[2-O-ethyltyrosine]-lysine-vasopressin inhibited the vasopressin-induced antidiuretic response. The antagonistic properties were further evaluated in long-term experiments on conscious non-hydrated rats with implanted minipumps. The analogues inhibited the vasopressin-induced antidiuresis at antagonist:agonist ratios of 0.5 and 1.0.

Alkylation↗
PubMed1980

Structure-activity studies on synthetic analogs to vasoactive peptides derived from human fibrinogen.

Counterparts to two vasoactive peptides previously isolated from fibrin(ogen) degraded by plasmin (EC 3.4.21.7) were synthesized by the solid phase procedure. The synthetic undecapeptide (Ser-Gln-Leu-Gln-Lys-Val-Pro-Pro-Glu-Trp-Lys) was isolated in a homogeneous state by chromatography on Sephadex G-25 and DEAE-Sepharose CL-6B and the pentapeptide (Ala-Arg-Pro-Ala-Lys) by chromatography on BioGel P-6 and column zone electrophoresis. The effect of these two peptides and of fifteen analogs to the pentapeptide on microvascular permeability in rat skin was investigated. The two synthetic counterparts were as potent as the natural peptides. With respect to the analogs, the influence of different functional groups was first studied. This was followed by attempts to minimize the active structure, induce or relieve rigidity of the peptide back-bone or otherwise accomplish modifications by a change in chirality at critical positions. Our results show that the tetrapeptide Arg-Pro-Ala-Lys has the same effect on microvascular permeability as the pentapeptide in the assay system used. Basic amino acids at both ends, as well as a proline residue adjacent to the N-terminal amino acid appear important for full or essentially full activity. On the other hand, substitution of the Ala at position 4 with several other amino acids did not result in a significant loss in biological potency.

Capillary Permeability↗
PubMed1980

Effect of O-alkylated analogues of lysine vasopressin on adenylate cyclase of pig kidney membranes.

O-alkylated analogues (ethyl, propyl, butyl, tert.-butyl) of lysine vasopressin (LVP) and deamino-LVP are partial agonists to LVP in their effect upon activation of adenylate cyclase in porcine kidney membranes. Emax and pD2 values are linearly dependent and both of them are inversely proportional to the overall hydrophobicity of the peptides, expressed in terms of capacity factors in reversed phase high performance liquid chromatography. It is suggested that the increasing hydrophobicity augments the tendency to either a "wrong way" binding, or to a side-side interaction of several peptide ligands bound to a multi-subsite receptor or both. The data circumstantially indicate that the relation between the peptide-receptor interaction and cyclase activation is not a linear one.

Adenylyl Cyclases↗
PubMed1978

Synthesis of O-alkylated lysine-vasopressins, inhibitors of the antidiuretic response to lysine-vasopressin.

[Mpa1,Tyr(Et)2]-LVP (1-deamino-2-O-ethyltyrosine-8-lysine-vasopressin), [Mpa1,Tyr(n-Pr)2]-LVP, [Tyr(n-Bu)2]-LVP, [Mpa1,Tyr(n-Bu)2]-LVP, and [Mpa1,Tyr(n-hexyl)2]-LVP were synthesized in solution by the p-nitrophenyl ester method. The previously prepared [Tyr(Et)2]-LVP was resynthesized. All compounds possessed weak agonistic properties in both antidiuretic (0.5-2.0 IU/mumol) and pressor (0.5-3.0 IU/mumol) assays. In the rat none of the analogues inhibited the antidiuretic action of LVP when the two substances were given together in a single injection. However, when administered in low subthreshold doses, most of the deamino compounds suppressed the antidiuresis induced by a continuous infusion of LVP. Complete inhibition was obtained with [Mpa1,Tyr(Et)2]-LVP. The antagonistic potency seemed to decrease with increasing size of the alkyl substituent and [Mpa1,Tyr(n-hexyl)2]-LVP showed no antagonism. The molar inhibitor-LVP ratio for maximal inhibition was well below 100. Neither of the two amino analogues showed a clear-cut antagonism in the antidiuretic assay. Furthermore, none of the reported compounds was antagonistic to LVP in the rat pressor assay.

Animals↗
PubMed1977

Pectinolytic ability of some mycorrhizal and saprophytic hymenomycetes.

Ectomycorrhizal fungi of the genus Boletus were able to use a restricted number of hexoses and disaccharides as single carbon sources. In the presence of a small amount of "start" glucose, induced growth occurred on a few additional carbohydrates. Even in the presence of "start" glucose, the ectomycorrhizal fungi could not utilize pectin, whereas certain litter-decomposing fungi grew rapidly using this compound as a carbon source. Only the litter-decomposers were able to use galacturonic acid, the monomer of pectic acid, as a carbon source. Possible mechanisms for the penetration and growth of ectomycorrhizal fungi into the middle lamellae of the root parenchyma are discussed.

Agaricales↗
PubMed1977

Solid phase synthesis and some hormonal activities of 1-deamino-4-L-valine-8-D-homolysine-and 1-deamino-4-L-valine-8-D-homoarginine-vasopressin.

1-Deamino-4-L-valine-8-DL-homolysine-vasopressin and protected 1-deamino-4-l-valine-8-D-lysine-vasopressin were synthesized by the solid phase method and were then converted into the title compounds (dVDHLVP and dVDHAVP) by tryptic digestion and epsilon-guanidination, respectively. The new hormone analogues exhibit only moderate antidiuretic potency, dVDHLVP 21 units/mg and dVDHAVP 31 units/mg, but since they are essentially devoid of pressor activity (o.o1 units/mg/ the A/P ratios are very high. In fact, dVDHLVP is the most specific antidiuretic agent in the lysine series known so far.

Amino Acid Sequence↗
PubMed1976

Solid phase synthesis and some pharmacological properties of 8-D-homoarginine-vasopressin and 1-deamino-8-D-homoarginine-vasopressin.

Fully protected 8-D-lysine-vasopresin and 1-deamino-8-D-lysine-vasopressin were synthesized by the solid phase method. Selective removal of the lysine protection and reaction with 1-guanyl-3,5-dimethylpyrazole converted D-lysine into D-homoarginine. The title compounds were then obtained by treatment with sodium in liquid ammonia and oxidation in dilute aqueous solution. Although the antidiuretic activities are lower than for the corresponding D-argining derivatives, the even lower pressor effects make the new analogues highly specific antidiuretic agents. The A/P ratios for 8-D-homoarginine-vasopressin and its 1-deamino derivative are 100 and 3,300, respectively.

Animals↗