Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 112 (1981), S. 1099-1102 
    ISSN: 1434-4475
    Keywords: Enzymatic peptide synthesis ; Thermitase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The utility of thermitase, a thermophilic proteolytic enzyme fromThermoactinomyces vulgaris, as a catalyst for peptide synthesis has been studied using several Nα-benzyloxycarbonyl dipeptide esters as carboxyl components and Leu-NH2 as nucleophile. Couplings were most successful with substrates containing Met, Leu, Ala, Phe, Tyr in P1-position, and Val, Ala, Pro in P2, whereas the substrates with Val, Ile, Pro in P1 failed to couple.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 112 (1981), S. 469-481 
    ISSN: 1434-4475
    Keywords: Biphasic aqueous-organic solvent mixtures ; α-Chymotrypsin ; Immobilized enzymes ; Peptide synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Kovalent an Kieselgel, Enzacryl AA und Enzacryl AH gebundenes α-Chymotrypsin katalysiert die Peptidbindungsknüpfung zwischen N-geschützten Dipeptid-Methylestern und H-Leu-NH2 mit ähnlichen Ergebnissen wie das freie Enzym. Es wird gezeigt, daß mit Wasser mischbare und nichtmischbare Lösungsmittel, die Trägermaterialien sowie die Struktur der Substrate den Verlauf der Chymotrypsin-katalysierten Kupplungsreaktionen beeinflussen. Die besten Ausbeuten wurden in wäßrig-organischen Zweiphasen-systemen mit Kieselgel-gebundenem Chymotrypsin und mit Substraten mit Leucin in P2-Position erhalten. Die Syntheseausbeuten werden in bezug auf die Reaktivität von Substraten ähnlicher Struktur bei der enzymatischen Hydrolyse diskutiert. Alle immobilisierten Chymotrypsin-Präparationen konnten mit Erfolg für weitere Kupplungsreaktionen wiedergenutzt werden.
    Notes: Abstract α-Chymotrypsin covalently bound to silica, enzacryl AA, and enzacryl AH catalyzes peptide bond formation between N-protected dipeptide methyl esters and H-Leu-NH2 with results similar to those with the free enzyme. The influence of water-miscible and water-immiscible cosolvents, of the supports, and of the structure of the substrates is shown to be of importance for the ease of the chymotrypsin-medicated coupling reactions. The best yields were obtained using biphasic aqueous-organic solvent mixtures, silica-bound chymotrypsin, and substrates with leucine in the P2-position. The yields of the syntheses are discussed in terms of the reactivity of substrates with similar structure in enzymatic hydrolyses. All the immobilized chymotrypsin preparations could be re-utilized successfully for further couplings.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    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.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1434-4475
    Keywords: Enzymatic peptide synthesis ; Arginine peptides ; Papain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The papain-catalyzed reaction of esters of Z-alanine with various arginine esters was investigated. Using H-Arg-OPr i as a nucleophile the expected dipeptide product results in high yield. Otherwise, reactions with arginine esters of primary alkohols provide products undergoing further reactions. This allows the synthesis of N-protected peptide esters containing two or more arginine residues in a one-step reaction. The influence of reaction conditions on the process was investigated.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 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.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1434-4475
    Keywords: Immobilized enzymes ; Papain ; Peptide synthesis ; Thermolysin ; Trypsin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Model studies were performed on the utility of covalently immobilized trypsin, thermolysin and papain for peptide bond formation. Trypsin and thermolysin catalyzed the formation of peptide bonds with nearly the same efficiency as the soluble proteases and they could be re-used successfully for further coupling experiments. The possibility of using immobilized trypsin and papain for kinetically controlled peptide bond formation was investigated. With the serine type enzyme trypsin excellent product yields were obtained starting with ester carboxyl components and an economical ratio of substrates. Experiments with the thiol protease papain were unsatisfactory because the once formed product is hydrolyzed as fast as the starting ester substrate used.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    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.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1434-4475
    Keywords: α-Chymotrypsin ; Enzymatic peptide synthesis ; Papain ; Solidphase peptide synthesis ; Thermolysin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Thermolysin, α-Chymotrypsin und Papain wurden als Biokatalysatoren für die Kupplung verschiedener Carboxylkomponenten an kieselgel-gebundenes Leucinamid als Nucleophil eingesetzt. Für erfolgreiche Kupplungen war eine Spacerlänge von 21 kovalenten Bindungen entsprechend 7 Aminosäureresten erforderlich. Diese Synthesevariante eröffnet die Möglichkeit, racemisierungsfreie Segmentkondensationen an unlöslichen polymeren Trägern mit Hilfe von Proteasen durchzuführen.
    Notes: Abstract Thermolysin, α-chymotrypsin, and papain were used as biocatalysts for the coupling of several carboxyl components to silica-supported leucine amide as a nucleophile. A spacer length of 21 covalent bonds corresponding to 7 amino acid residues was required for successful coupling. This approach offers the possibility of using proteases for racemization-free segment condensations on insoluble polymeric supports.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1434-4475
    Keywords: Chymotrypsin ; Enzymatic peptide synthesis ; Liquid phase peptide synthesis ; Solubilizing protective groups ; Polyoxyethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The utility of amino acids and dipeptides esterified to solubilizing polyoxyethylene supports as substrates for protease-mediated peptide bond formation was studied using free and immobilized α-chymotrypsin as a catalyst. Poor yields were obtained with Nα-protected amino acid or dipeptide polyoxyethylene esters as carboxyl components, most probably due to a shielding of the active site of the acyl enzyme intermediate by the polymer favouring hydrolytic cleavage. Experiments with polyoxyethylene esters as nucleophiles gave good results with free chymotrypsin, immobilized chymotrypsin predominantly caused hydrolysis of the ester carboxyl component due to unfavourable interactions between the soluble and insoluble polymers.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    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.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...