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  • 1
    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
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  • 2
    ISSN: 0006-3592
    Keywords: protease ; acyl transfer ; nucleophile efficiency ; inverse substrates ; trypsin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Benzyloxycarbonyl-L-alanine p-guanidinophenyl ester behaves as a trypsin “inverse substrate,” i.e., a cationic center is included in the leaving group instead of being in the acyl moiety. Using this substrate as an acyl donor, trypsin catalyzes the synthesis of peptide bonds that cannot be split by this enzyme. An optimal acyl transfer efficiency was achieved between pH 8 and 9 at 30°C.The addition of as much as 50% cosolvent was shown to be of minor influence on the acyl transfer efficiency, whereas the reaction velocity decreases by more than one order of magnitude. The efficiency of H-Leu-NH2 and H-Val-NH2 in deacylation is almost the same for “inverse” and normal type substrates.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 319-321 
    ISSN: 0006-3592
    Keywords: Protease ; acyl transfer ; nucleophile efficiency ; inverse substrates ; trypsin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Benzyloxycarbonyl-L-proline p-guanidinophenyl ester is an “inverse substrate” for trypsin; i.e., the cationic center is included in the leaving group instead of being in the acyl moiety. This substrate can be used in trypsin-catalyzed acyl-transfer reactions leading to the synthesis of Pro-Xaa peptide bonds. The reaction proceeds about 20 times slower than reaction with similar alanine-containing substrates, but the ratio between synthesis and hydrolysis is more favorable. The investigation of a series of nucleophiles led to information about the specificity of the process. Nucleophiles differing only in the P1′-position show an increasing acyl transfer efficiency in the order Phe 〈 Gly 〈 Ley 〈 Ser 〈 Ala 〈 lle. C terminal elongation of the nucleophiles is of minor influence on their efficiency. The formation of an H bond between the acyl-enzyme and the nucleophile seems to play an important role in the aminolysis of the acyl-enzyme.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 432-436 
    ISSN: 0006-3592
    Keywords: theory of enzymatic peptide synthesis ; progress curve kinetics ; papain-catalyzed peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The published theory of kinetically controlled enzymatic peptide synthesis needed experimental verification. We carried out the measurement of the peptide yield and estimation of the key parameters α and β for papain-catalyzed synthesis of Mal-L-Phe-L-Ala-LLeuNH2 from Mal-L-Phe-L-AlaOMe and L-LeuNH2. The experimental results demonstrate that this theory adequately describes the real process. © 1992 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trotz des enormen Fortschritts bei der Synthese von Peptiden und Proteinen mit kommerziellen Peptidsynthesizern und der großen biotechnologischen Möglichkeiten der DNA-Rekombinationstechnik ist zur racemisierungssicheren Verknüpfung von Peptidsegmenten eine C-N-Ligase ein wichtiges Hilfsmittel. Da die Aktivierung der α-Carboxyfunktion eines Peptidsegmentes mit dem partiellen Verlust der Enantiomerenreinheit verbunden sein kann, bergen chemische Verknüpfungen von Peptidsegmenten Racemisierungsgefahren. Die Natur hat zur Synthese der riesigen Sequenzvielfalt von Peptiden und Proteinen mit der Peptidyltransferase nur ein einziges Enzym entwickelt, das unabhängig vom Charakter der Seitenkettenfunktionen der proteinogenen Aminosäurebausteine seine volle katalytische Funktion entfaltet. Jedoch ist die Peptidyltransferase nur als integraler Bestandteil des Ribosoms in einer koordinierten Interaktion mit anderen ribosomalen Faktoren wirksam, d.h. für die enzymatische Synthese nicht zu verwenden. Alternativ bieten sich für enzymatische Peptidsynthesen, wenn man von den eingeschränkten Möglichkeiten der Nutzung von Multienzymkomplexen der bakteriellen Peptidsynthese absieht, nur noch die Proteasen an, die aber aufgrund ihrer in-vivo-Funktion als Hydrolasen keine idealen C-N-Ligasen sein können. Erst gezielte thermodynamische und reaktionskinetische Manipulationen ermöglichen die Umkehrung der Proteasewirkung und damit eine Programmierung in Richtung Ligation. Ohne Zweifel ist eine synthesebegünstigende Einflußnahme bei einer durch Serin- und Cysteinproteasen katalysierten kinetisch kontrollierten Reaktionsführung variabler und effizienter zu realisieren als bei gleichgewichtskontrollierten Synthesen. Dieser Beitrag beschreibt den Einfluß der Enzymspezifität auf die Effizienz von kinetisch kontrollierten Synthesen. Es werden Schlußfolgerungen für eine breitere Nutzung von Serin- und Cysteinproteasen zur Katalyse von C-N-Verknüpfungen abgeleitet.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0570-0833
    Keywords: Enzyme catalysis ; Peptide synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In spite of the enormous progress in the synthesis of peptides and proteins using commercial peptide synthesizers and the immense technological possibilities of recombinant DNA technology, a C—N ligase is an indispensable tool for the racemization-free fragment condensation of peptides. Since activation of the C-terminal α-carboxyl group of a peptide segment could cause partial racemization, chemical condensations of peptide fragments are prone to racemization. For the synthesis of the huge number of peptides and proteins, however, nature has only developed the ribosomal peptidyltransferase, which exhibits its full catalytic function independent of the side-chain functions of the amino acids being coupled. However, its function requires coordination with numerous other ribosomal factors. Besides the limited possibilities of using multienzyme complexes of bacterial peptide synthesis systems, the only alternatives to peptidyltransferase are proteases, which, based on their in vivo function as hydrolases, cannot act as ideal ligases. However, by exploiting the intrinsic reversibility of hydrolytic reactions and by adjusting appropriate physicochemical reaction parameters, the protease acitivity can be used in the direction of ligation. Undoubtedly, the course of kinetically controlled, serine and cysteine protease-catalyzed reactions can be more efficiently influenced than the equilibrium-controlled protease-catalyzed synthesis. This article describes the influence of the enzyme specificity on the efficiency of kinetically controlled synthesis and points the way toward a broad exploitation of serine and cysteine proteases for the catalysis of C—N bond formation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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