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  • inhibitory specificity  (3)
  • FN-lamininase  (1)
  • HIV infection  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Semisynthesis of Arg15, Glu15, Met15, and Nle15-aprotinin involving enzymatic peptide bond resynthesis (1989)
    Springer
    The protein journal 8 (1989), S. 101-113 
    Details
    ISSN: 1573-4943
    Keywords: aprotinin ; bovine pancreatic trypsin inhibitor ; semisynthesis ; inhibitory specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The semisynthesis of homologues of aprotinin, the bovine pancreatic trypsin inhibitor, is described. The P1 lysine15 residue was replaced by two methods. The first procedure, which consisted of two enzymatic steps for the incorporation of other amino acids has previously been described. The second approach consisted of six steps of both enzymatic and chemical nature. The modified inhibitor, in which the lysine15-alanine16 peptide bond is hydrolyzed, was used as the starting material. All carboxyl groups of the modified inhibitor were esterified with methanol; the lysine15 methylester group was then selectively hydrolyzed. Afterward, lysine15 itself was split off. Arginine, glutamic acid, methionine, andl-2-aminohexanoic acid (norleucine, Nle) were incorporated using water-soluble carbodiimide combined with an acylation catalyst. The methylester group was used to prevent polymerization. The reactive-site peptide bonds were resynthesized using either chymotrypsin or trypsin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01025082
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  • 2
    Electronic Resource
    Electronic Resource
    The Proteolytic Activity and Cleavage Specificity of Fibronectin-Gelatinase and Fibronectin-Lamininase (1999)
    Springer
    The protein journal 18 (1999), S. 403-411 
    Details
    ISSN: 1573-4943
    Keywords: Fibronectin ; FN-gelatinase ; FN-lamininase ; retroviral aspartic proteinases ; α2-macroglobulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Human plasma fibronectin contains two latent aspartic proteinases, FN-gelatinase and FN-lamininase. Both enzymes can be generated and activated in the presence of Ca2+ from the purified cathepsin D-produced 190-kDa fibronectin fragment. We investigated the proteolytic activity and cleavage specificity of both enzymes in a range of pH from 3.5 to 9.0 using the B chain of oxidized bovine insulin and chromogenic peptides as substrates. The inhibition of the enzymes by several natural inhibitors from human plasma was also tested. The specificities of FN-gelatinase and FN-lamininase are similar to other major acidic proteinases, including pepsin, renin, cathepsin D, and HIV-proteinases. Both enzymes mainly hydrolyze three peptide bonds in the oxidized insulin B chain, namely Glu–Ala (residues 13–14), Tyr–Leu (residues 16–17), and Phe–Phe (residues 24–25). For the peptide substrates H-Pro-Thr-Glu-Phe-p-nitro-Phe-Arg-Leu-OH and H-Phe-Gly-His-p-nitro-Phe-Phe-Val-Leu-OMe that were cleaved the respective values of k cat/K M were 105.1 and 11.8 mM−1 sec−1 for cleavage by FN-gelatinase, and 123.2 and 15.5 mM−1 sec−1 for cleavage by FN-lamininase. The maximal activities of both enzymes were observed in a range between pH 5.6 and 6.3 and they became inactivated at a pH value above 8.4. Both FN-gelatinase and FN-lamininase were efficiently inhibited by α2-macroglobulin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020684508212
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymatic semisynthesis of aprotinin homologues mutated in P′ positions (1991)
    Springer
    The protein journal 10 (1991), S. 245-251 
    Details
    ISSN: 1573-4943
    Keywords: Aprotinin ; bovine pancreatic trypsin inhibitor ; enzymatic synthesis ; semisynthesis ; inhibitory specificity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The replacement of amino acids in the P′1 and P′2 position of aprotinin, the bovine pancreatic trypsin inhibitor, is described. Using the “modified” inhibitor as starting material, with the hydrolyzed reactive-site peptide bond Lys15-Ala16, the residues P′1 (Ala16) and P′2 (Arg17) were split off by the action of aminopeptidase K. Incorporation of suitable dipeptides containing a basic residue (Lys or Arg) in the C-terminal position was carried out in a “one pot” reaction involving trypsin-catalyzed coupling. In this way, the native fragment Ala16-Arg17 was reintroduced and also replaced by Gly-Arg, Ala-Lys, and Leu-Arg yielding intact inhibitor molecules. The mechanism for incorporation of dipeptides was investigated by treating the aprotinin derivative with the Arg17-Ile18 peptide bond hydrolyzed with trypsin under proteosynthetic conditions. We established that only inhibitor molecules cleaved between Lys15 and Xaa16 are intermediates leading to the desired products. The inhibitory properties of the new aprotinin homologues were tested, and the significance of the P′1 residue for the inhibition of trypsin, kallikrein, and chymotrypsin was deduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024788
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical semisynthesis of aprotinin homologues and derivatives mutated inp′ positions (1991)
    Springer
    The protein journal 10 (1991), S. 527-533 
    Details
    ISSN: 1573-4943
    Keywords: Aprotinin ; bovine pancreatic trypsin inhibitor ; semisynthesis ; inhibitory specificity ; kallikrein inhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An extended concept for the replacement of amino acids in theP' region of aprotinin by chemical semisynthesis is presented. Either fragment condensation with dipeptides protected as tert-butyl ester or stepwise introduction of two single amino acid-tert-butyl esters into a partially esterified aprotinin derivative (with free Lys15-carboxyl group) lacking the amino acids Ala16 and Arg17 leads to aprotinin homologues and derivatives mutated in theP′ 1 andP′ 2 position. This method may complement the recently reported enzymatic synthesis by enabling access to aprotinin homologues and derivatives, which cannot be prepared enzymatically. The synthesis of [Ala17]BPTI and [seco-17/18]BPTI is described in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01025481
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  • 5
    Electronic Resource
    Electronic Resource
    Inhibition of Tryptase TL2 from Human T4+ Lymphocytes and Inhibition of HIV-1 Replication in H9 Cells by Recombinant Aprotinin and Bikunin Homologues (1997)
    Springer
    The protein journal 16 (1997), S. 651-660 
    Details
    ISSN: 1573-4943
    Keywords: Kunitz-type inhibitor ; aprotinin ; bikunin ; tryptase TL2 ; HIV infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The serine esterase TL2 from human T4+ lymphocytes is a binding component to HIV-1 glycoprotein gp120 and seems to play a role in the HIV-1 infection mechanism. Recombinant variants of the Kunitz-type serine proteinase inhibitor aprotinin were investigated for their ability to inhibit tryptase TL2 and the binding of gp120 to this enzyme. Furthermore, the viral replication of HIV-1 was investigated in H9 cell cultures under the influence of recombinant aprotinin and bikunin variants. In contrast to native aprotinin, the recombinant variant [Arg15, Phe17, Glu52]aprotinin with a reactive-site sequence homologous to the V3 loop of HIV-1 gp120 showed a specific inhibition of tryptase TL2 (〉80%). However, the [Leu15, Phe17, Glu52]aprotinin variant with hydrophobic subsites was the most potent inhibitor of the binding of gp120 to tryptase TL2 (68%). Our results show that the enzyme activity of purified tryptase TL2 is inhibited not only by variants with basic amino acids, but also those with hydrophobic residues in the reactive-site region. Therefore, tryptase TL2 is not a typical trypsin-like or chymotrypsin-like protease. Investigations on inhibition of HIV-1 replication in H9 cell cultures showed that tryptase TL2 is involved in the mechanism of virus internalization into human lymphocytes. The [Leu15, Phe17, Glu52]aprotinin showed a significant retardation of syncytium formation over a period of 5 days in a 1 μM concentration. Similar investigations were performed with recombinant variants of bikunin, the light chain of human inter-α-trypsin inhibitor. Only the single-headed variant [Arg94]82bikunin inhibited slightly the syncytium formation over a period of 2 days in a 2.2 μM concentration. Wild-type bikunin and all full-length variants showed no effect, possibly due to steric hindrance by the second domain of the double-headed inhibitor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026379109403
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