Zur Synthese des Glucagons, X. Darstellung der Sequenz 22–29

Wünsch, Erich; Drees, Fritz

doi:10.1002/cber.19660990119

Cited by 193 publications

(38 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1) and the methylester of N-glutarylgramicidin were prepared by reaction of desformyl-gramicidin with the dicarboxylic acid monomethylester in the presence of N,N'-dicyclohexylcarbodiimide (Wfinsch & Drees, 1966). 0.25 mmol desformylgramicidin, 0.26 mmol N,N'-dicyclohexylcarbodiimide, 0.5 mmol Nhydroxysuccinimide, and 0.33 mmol dicarbonic acid monomethylester (or monoethylester) were dissolved in 5 ml absolute dimethylacetamide and 5 ml hexamethylphosphoric acid triamide at -15 ~ After stirring for 1 hr at -15 ~ the solution was kept overnight at 3 ~ for three days at 20 ~ and then stirred for 30 min at 60 ~ After precipitation with water and centrifugation, the reaction product was dissolved in methanol.…”

Section: Preparation ()[ the Gramicidin Analogsmentioning

confidence: 99%

Dicarboxylic acid analogs of Gramicidin A: Dimerization kinetics and single channel properties

1979

View full text Add to dashboard Cite

According to the model of Urry, the cation-permeable gramicidin channel is a dimeric helix formed by association of two peptide monomers linked at their amino ends. In this paper the channel properties of gramicidin analogs are described which have been obtained by chemical modification at the coupling site of the two half-channels. In these analogs the amino terminal -CHO group is replaced by -CO(CH2)nCCOH (n = 2, 3, 4, 5, 6). All analogs form conducting channels in black lipid membranes with the same general properties as found for gramicidin A. The observation that the channel-forming activity decreases with increasing pH is consistent with the notion that the half-channels are linked at the amino terminus. The channel lifetime of the different analogs varies between 2 msec and greater than of equal to 50 sec, the longest lifetime being found for the compound with n = 3. The single-channel conductance : formula : (see text) is always smaller than that of gramicidin A, but the reduction of : formula : (see text) depends on the nature of the permeable ion. Ion specificity was studied at 1 M electrolyte by measuring the conductance : formula : (see text) for different permeable ions (Na+, K+, Cs+). The conductance ration : formula : (see text) (Cs+)/ : formula : (see text) (Na+) was found to vary between 2 and 10.5 for the different analogs.

show abstract

Section: Preparation ()[ the Gramicidin Analogsmentioning

confidence: 99%

Dicarboxylic acid analogs of Gramicidin A: Dimerization kinetics and single channel properties

1979

View full text Add to dashboard Cite

show abstract

“…(ii) DCCI-HONSLI (18) anhydride coupling of the benzyl ester. The product was As for the DCCI coupling except that HONSu (57 mg) washed with ether and dried in vacrro over KOH.…”

Section: Co~ipling Meflrods For Rncenrizntio?~ Experirilerrfsmentioning

confidence: 99%

N-Methylamino Acids in Peptide Synthesis. IV. Racemization and Yields in Peptide-bond Formation

McDermott¹,

Benoiton²

1973

Can. J. Chem.

View full text Add to dashboard Cite

The racemization of an N-methylamino-acid residue during peptide-bond formationand mixed-anhydride activation has been investigated using Ala-MeLeu-Gly and Ala-MeLeu as model peptides. The results were compared with those for Ala-Leu-Gly, Ala-Leu, and Ala-Pro. The extents of racemization were determined by analysis of the diastereomeric products of the reactions after deprotection, using an amino-acid analyzer. Extensive racemization was detected after the hydrolysis of the mixed anhydrides of Bz-MeLeu, Z-Ala-MeLeu, and Z-Ala-Leu, but not of Boc-Ala-Pro and Z-MeIle. Significant racemization (2.8-39%) was observed when Z-Ala-MeLeu was coupled with Gly-OBzl by various methods in the presence of salts such a s triethylamine hydrochloride orp-toluenesulfonate. Only coupling through the N-hydroxysuccinimide (HONSu) ester gave stereochemically pure product. In the absence of salt, less racemization was observed, but only couplings using N-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline and N,N1-dicyclohexylcarbodiimide-HONSu gave essentially pure products. Polar solvents promoted racemization, but excess base did not. Chemical evidence that the racemization intermediate is an oxazolium-5-oxide has been obtained by trapping the intermediate a s an addition product (a pyrrole) in 85% yield.The yields obtained by various coupling methods have been determined for several model peptides. Couplings at the carboxyl group of an N-methylamino acid gave high yields only in the absence of salt, except for coupling by the HONSu ester method. Couplings to an N-methylamino group gave high yields, except for coupling by thep-nitrophenyl ester method. Couplings to Ala-MeLeu-OBu' gave higher yields than couplings to Ala-MeLeu-OBzl, presumably due to piperazine-dione formation by the latter. Une racemisation importante a CtC dCtectte apres hydrolyse des anhydrides mixtes de Bz-MeLeu, Z-Ala-MeLeu et Z-Ala-Leu mais pas pour Boc-Ala-Pro e t Z-MeIle. Une racemisation notables (2.b39%) a etC observCe lors du couplage du Z-Ala-MeLeu sur le Gly-OBzl par les diverses mithodes en prisence de sels tels que le chlorohydrate ou para toluene sulfonate de triethylamine. Seul le couplage par I'ester d e La N-hydroxy succinimide (HONSu) conduit 2 un produit d e puretC sttreochimique. En l'absence de sel, la racemisation est plus faible mais seuls les couplages par le NCthoxycarbonyl Cthoxy-2 dihydro-1,2 quinoleine et le complexe N,N'-dicyclohexylcarbodiimide-HONSu donnent des produits essentiellement purs. Les solvants polaires favorisent la racCmisation mais pas un exces d e base. L'intermCdiaire de racemisation oxyde-5 d'oxazolium a it6 rnis en evidence par piegeage sous forme de produits d'addition (un pyrrole) avec un rendement de 85%.Les rendements obtenus dans les divers couplages ont ete dCterminCs sur differents peptides modeles.

show abstract

“…Numerous methods have been reported for the preparation of amides. The most typical procedures are the Yasutsugu Shimonishi method, the N-carboxyl anhydride (NCA) method, and the DCC-HOSu method [5][6][7][8]. Organic phosphorus coupling reagents [9][10][11] also have been applied for the synthesis of amides, such as the Appel [12] coupling reagents (triphenylphosphine and hexachloroethane).…”

Section: Introductionmentioning

confidence: 99%

Syntheses, characterizations, and crystal structures of phosphonopeptides

Fang

Liu

et al. 2007

Heteroatom Chemistry

View full text Add to dashboard Cite

alpha-Aminophosphonic acids and their derivatives, as phosphorus analogs of amino acids, have attracted much attention as they show a range of biological activities. In this paper, dialkyl phenyl(4-pyridylcarbonylamino)methylphosphonates were synthesized via the Mannich reaction (Yuan et al., Synthesis 1990, 3, 256) and peptide coupling. Their structures were confirmed by elemental analysis, IR, H-1 NMR, C-13 NMR, and MS. X-ray diffraction data of compounds (2a, 2b, 2c) were reported respectively. The antibacterial and antitumor activities of these compounds are first reported in this paper. (c) 2007 Wiley Periodicals, Inc

show abstract

Zur Synthese des Glucagons, X. Darstellung der Sequenz 22–29

Cited by 193 publications

References 14 publications

Dicarboxylic acid analogs of Gramicidin A: Dimerization kinetics and single channel properties

Dicarboxylic acid analogs of Gramicidin A: Dimerization kinetics and single channel properties

N-Methylamino Acids in Peptide Synthesis. IV. Racemization and Yields in Peptide-bond Formation

Syntheses, characterizations, and crystal structures of phosphonopeptides

Contact Info

Product

Resources

About