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  • 1
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 117 (1986), S. 1195-1204 
    ISSN: 1434-4475
    Keywords: Carboxamidomethyl ester as C-protecting group ; Enzymatic deprotection ; Peptide synthesis ; α-Chymotrypsin- and Papain-catalyzed peptide bond formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Carboxamidomethylester (CAM-Ester) vonZ- undBoc-geschütztem Alanin und Phenylalanin hergestellt mit dem Ziel, ihre Eignung als Substrate für α-chymotrypsin- und papainkatalysierte Hydrolyse- sowie Peptidsynthesereaktionen zu untersuchen. Die leichte, unter milden Bedingungen und in Abhängigkeit von der Enzymspezifität erfolgende Abspaltung derCAM-C-Schutzgruppe wurde nachgewiesen. An Beispielen wird die proteasekatalysierte Synthese verschiedener Peptidderivate unter Verwendung vonCAM-Estern als C-und N-Komponenten in wäßrig-organischen Medien belegt. Die für die Umsetzungen benötigten Reaktionszeiten sind vergleichsweise gering.
    Notes: Abstract Carboxamidomethyl esters (CAM esters) ofZ- andBoc-protected alanine and phenylalanine were prepared in order to investigate their usefulness as substrates for α-chymotrypsin- and papain-catalyzed hydrolysis and peptide synthesis reactions. The easy removal of theCAM-C-protecting group under mild conditions and dependent on the enzyme specificity was demonstrated. Examples are given for the protease-catalyzed synthesis of various peptide derivatives usingCAM esters as C- and N-components in aqueous-organic media. Comparatively short reaction times were observed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 118 (1987), S. 1279-1288 
    ISSN: 1434-4475
    Keywords: Enzymatic synthesis in biphasic systems ; Peptide synthesis ; α-Chymotrypsin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die DipeptidderivateZ-Tyr-Leu-NH2 undMca-Tyr-Leu-NH2 wurden durch α-chymotrypsin-katalysierte Kupplung in biphasischen Systemen aus Puffer und Essigsäureethylester hergestellt. Im Vergleich zu einem rein wäßrigen Medium, in dem nahezu keine Synthese erfolgt, wird in einem biphasischen System die Synthesereaktion durch Extraktion des Dipeptids in die organische Phase wesentlich begünstigt. Es wurde der Einfluß verschiedener Reaktionsparameter, wie Pufferkonzentration, Reaktionszeit, Volumenverhältnis von organischer zu wäßriger Phase und Reaktandenkonzentration auf die Ausbeute anZ-Tyr-Leu-NH2 untersucht. Ein Austausch der hydrophobenZ-Gruppe gegen die hydrophilere Chloracetylgruppe führte zu besseren Dipeptidausbeuten bei höheren Reaktionsgeschwindigkeiten.
    Notes: Abstract The dipeptide derivativesZ-Tyr-Leu-NH2 andMca-Tyr-Leu-NH2 were synthesized by α-chymotrypsin-catalyzed coupling reactions in solvent systems consisting of buffer and ethyl acetate. In comparison to a pure aqueous medium, in which only insignificant synthesis takes place, the product formation is greatly enhanced in a biphasic medium due to extraction of the dipeptide into the organic phase. The influence of several reaction parameters, such as buffer concentration, reaction time, volume ratio of organic and aqueous phase, and reagent concentration on the yield ofZ-Tyr-Leu-NH2 was investigated. Replacement of the hydrophobicZ-group by the more hydrophilic chloroacetyl group resulted in better dipeptide yields at higher reaction rates.
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  • 5
    ISSN: 1434-4475
    Keywords: Enzymic synthesis in biphasic systems ; Peptide synthesis ; α-Chymotrypsin ; Papain ; Thermolysin ; Protected Eledoisin (6–11)-hexapeptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Papain and α-chymotrypsin were used for the protease-catalyzed assembly ofBoc-protected eledoisin (6−11)-hexapeptide by (2+4)- and (3+3)-segment condensation, respectively, in aqueous-organic solvent systems. As C-components, chemically synthesizedBoc-protected peptide methyl esters were employed. The nucleophilic tetrapeptide amide was prepared by papain-catalyzed (2+2)-segment coupling, while theZ-protected C-terminal dipeptide amide could be obtained by α-chymotrypsin- and thermolysin-catalyzed peptide bond formation. In addition, the influence of various reaction conditions, such as solvent composition, nucleophile concentration and reaction time, on the yield of theBoc-protected eledoisin (6−11)-hexapeptide was determined.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 112 (1981), S. 1165-1173 
    ISSN: 1434-4475
    Keywords: Enzymic synthesis in biphasic systems ; Papain-catalyzed peptide bond formation ; Peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Several model peptides have been synthesized enzymatically using papain as a catalyst in biphasic aqueous-organic systems. The effect of different cosolvents,pH, buffer concentration, and reaction time on the papaincatalyzed synthesis was examined. A comparison of the results obtained indicates that water-immiscible organic solvents provide higher yields than methanol in papain mediated peptide synthesis with carboxyl components in the carboxyl free form. Furthermore, it could be established that papaincatalyzed peptide synthesis can be considerably speeded up by employing acyl peptide esters instead of acyl peptides. The former should promote the rapid formation of the acyl-enzyme intermediate.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 114 (1983), S. 571-579 
    ISSN: 1434-4475
    Keywords: Enzymic synthesis in biphasic systems ; Pepsin-catalyzed peptide bond formation ; Peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The usefulness of biphasic aqueous-organic solvent systems for pepsin-catalyzed synthesis of model peptidesZ-X-Phe-Phe-OMe (X=Ala, Gln, Leu) has been demonstrated by coupling the correspondingZ-X-Phe-OH with H-Phe-OMe. The influence of various organic solvents on pepsin activity was examined. Some examples are given for the influence of nucleophile and enzyme concentration, bufferpH and organic solvent portion on product yield. Tetrachloromethane and mixtures of ethyl acetate/n-hexane proved to be especially useful allowing syntheses in good yields and within comparatively short reaction times of 2–6 hours.
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  • 8
    ISSN: 1434-4475
    Keywords: Carboxypeptidase Y catalyzed peptide bond formation ; Enzymic synthesis in biphasic systems ; Peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Carboxypeptidase Y katalysiert in einem Zweiphasensystem aus Tetrachlormethan und Carbonatpuffer die Reaktion vonZ-Phe-OMe und verschiedenenZ- undBoc-geschützten Dipeptidmethylestern mit Val-NH2 bzw. Leu-NH2. Nach diesem Verfahren werden die entsprechenden N-geschützen Tripeptidamide in präparativem Maßstab hergestellt. Bei einem Substrat-Nucleophil-Verhältnis von nur 1:2 oder 1:3 erhält man die Peptidderivate in Ausbeuten von 56–97%.
    Notes: Abstract Carboxypeptidase Y catalyzes in a biphasic system containing carbon tetrachloride and carbonate buffer the reaction ofZ-Phe-OMe and variousZ-andBoc-protected dipeptide methyl esters with Val-NH2 and Leu-NH2, respectively. This method has been applied to the synthesis of the corresponding N-protected tripeptide amides on a preparative scale. Using a substrate—nucleophile ratio of only 1:2 or 1:3 the peptide derivatives are obtained in yields of 56–97%.
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  • 9
    ISSN: 1434-4475
    Keywords: Enzymatic peptide synthesis ; Fmoc-protected amino acid derivatives ; Chymotrypsin ; Papain ; Thermolysin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Fmoc-Phe-OMe,Fmoc-Ala-OMe undFmoc-Gly-OH wurden unter katalytischer Wirkung von Chymotrypsin, Papain bzw. Thermolysin mit H-Leu-NH2 gekuppelt und der Einfluß verschiedener Reaktionsmedien und -parameter, wie Reaktanden- und Enzymkonzentration sowie Reaktionszeit, auf die Peptidbindungsbildung untersucht.
    Notes: Summary Fmoc-Phe-OMe,Fmoc-Ala-OMe andFmoc-Gly-OH were coupled with H-Leu-NH2 under catalytic action of chymotrypsin, papain and thermolysin, respectively. The influence of different reaction media and several reaction parameters, such as reactants and enzyme concentrations as well as reaction time, on the peptide bond formation was investigated.
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  • 10
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Protease Catalyzed and Chemical Peptide Bond Formation with α-Trifluoromethyl Substituted α-Amino AcidsSubtilisin, α-chymotrypsin and papain catalyzed hydrolyses of α-trifluoromethyl substituted N-benzyloxycarbonyl amino acid methylesters (Z-TFM-Xaa-OMe) 1 can be achieved only in the case of 3,3,3-trifluoroalanine. Enzymatic incorporation of Z-TFM amino acids 2 into N-terminal position of dipeptides also fails. In contrary, dipeptides with a TFM amino acid moiety in N-terminal position, e.g. TFM-Phg-L-Phe-OMe 5, react with H-Leu-NH2 to give the corresponding tripeptides 6 in high yield. Z protected dipeptide derivatives 8 with N-terminal TFM amino acids can be obtained via 4-trifluoromethyl-5-(4H)-oxazolones 7.
    Additional Material: 1 Ill.
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