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1.

001-es BibID:BIBFORM040647
Első szerző:Bláha, Ivo
Cím:Solid phase synthesis of the proteinase of bovine leukemia virus Comparison of its specificity to that of HIV-2 proteinase / Bláha Ivo, Tözsér József, Kim Young, Copeland Terry D., Oroszlan Stephen
Dátum:1992
ISSN:0014-5793
Megjegyzések:The 126-residue proteinase (PR) of bovine leukemia virus (BLV) was synthesized by solid-phase peptide synthesis and its activity was shown using various oligopeptide substrates representing cleavage sites in BLV, human T-cell leukemia virus type 1 (HTLV-1), murine leukemia virus (MuLV) and human immunodeficiency virus type 1 (HIV-1). The specificity of the BLV PR was also compared to that of chemically synthesized human immunodeficiency virus type 2 (HIV-2) PR. Many of the peptides were cleaved at the expected site, however, 6 out of 15 were hydrolyzed only by one of the PRs. Furthermore, one BLV peptide was processed differently by the two enzymes. These results, together with the relative activities and the lack of inhibition of BLV PR by two HIV-1 PR inhibitors, suggest that the BLV PR specificity is substantially different from that of HIV PRs.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Febs Letters. - 309 : 3 (1992), p. 389-393. -
További szerzők:Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Kim, Young Copeland, Terry D. Oroszlan, Stephen
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2.

001-es BibID:BIBFORM040648
Első szerző:Boross Péter (biokémikus, vegyész)
Cím:Effect of substrate residues on the P2' preference of retroviral proteinases / Boross Peter, Bagossi Peter, Copeland Terry D., Oroszlan Stephen, Louis John M., Tozser Jozsef
Dátum:1999
ISSN:0014-2956
Megjegyzések:The substrate sequence requirements for preference toward P2' Glu residue by human immunodeficiency virus type 1 (HIV-1) proteinase were studied in both the matrix protein/ capsid protein (MA/CA) and CA/p2 cleavage site sequence contexts. These sequences represent typical type 1 (-aromatic*Pro-) and type 2 (-hydrophobic* hydrophobic-) cleavage site sequences, respectively. While in the type 1 sequence context, the preference for P2' Glu over Ile or Gln was found to be strongly dependent on the ionic strength and the residues being outside the P2-P2' region of the substrate, it remained preferable in the type 2 substrates when typical type 1 substrate sequence residues were substituted into the outside regions. The pH profile of the specificity constants suggested a lower pH optimum for substrates having P2' Glu in contrast to those having uncharged residues, in both sequence contexts. The very low frequency of P2' Glu in naturally occurring retroviral cleavage sites of various retroviruses including equine infectious anemia virus (EIAV) and murine leukemia virus (MuLV) suggests that such a residue may not have a general regulatory role in the retroviral life cycle. In fact, unlike HIV-1 and HIV-2, EIAV and MuLV proteinases do not favor P2' Glu in either the MA/CA or CA/p2 sequence contexts.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 264 : 3 (1999), p. 921-929. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Copeland, Terry D. Oroszlan, Stephen Louis, John M. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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3.

001-es BibID:BIBFORM040653
035-os BibID:PMID:2190554
Első szerző:Copeland, Terry D.
Cím:Substitution of proline with pipecolic acid at the scissile bond converts a peptide substrate of HIV proteinase into a selective inhibitor / Terry D. Copeland, Ewald M. Wondrak, Jozsef Tozser, Michael M. Roberts, Stephen Oroszlan
Dátum:1990
ISSN:0006-291X
Megjegyzések:The nonapeptide H-Val-Ser-Gln-Asn-Tyr-Pro-Ile-Val-Gln-NH2 containing the retroviral Tyr-Pro cleavage site is a good substrate for the proteinase of human immunodeficiency viruses but it is not readily hydrolyzed by other nonviral proteinases including the structurally related pepsin-like aspartic proteinases. Replacing the Pro by L-pipecolic acid (2-piperidinecarboxylic acid) converted the substrate into an effective inhibitor of HIV-1 and HIV-2 proteinases with IC50 of approximately 1 microM. This compound showed a high degree of selectivity in that it did not inhibit cathepsin D and renin.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Biochemical and Biophysical Research Communications 169 : 1 (1990), p. 310-314. -
További szerzők:Wondrak, Ewald M. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Roberts, Michael M. Oroszlan, Stephen
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4.

001-es BibID:BIBFORM040815
Első szerző:Copeland, Terry D.
Cím:Totally synthetic retroviral proteins : proteases and nucleic acid binding proteins / T. D. Copeland, I. Bláha, J. Tőzsér, S. Oroszlan
Dátum:1991
Tárgyszavak:Orvostudományok Elméleti orvostudományok előadáskivonat
Megjelenés:Peptides: Chemistry and Biology / eds. Smith, J. A., Rivier, J. E. - p. 717-718
További szerzők:Bláha, Ivo Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Oroszlan, Stephen
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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5.

001-es BibID:BIBFORM040655
Első szerző:Fehér Anita
Cím:Effect of sequence polymorphism and drug resistance on two HIV-1 Gag processing sites / Fehér Anita, Weber Irene T., Bagossi Péter, Boross Péter, Mahalingam Bhuvaneshwari, Louis John M., Copeland Terry D., Torshin Ivan Y., Harrison Robert W., Tözsér József
Dátum:2002
ISSN:0014-2956
Megjegyzések:The HIV-1 proteinase (PR) has proved to be a good target for antiretroviral therapy of AIDS, and various PR inhibitors are now in clinical use. However, there is a rapid selection of viral variants bearing mutations in the proteinase that are resistant to clinical inhibitors. Drug resistance also involves mutations of the nucleocapsid/p1 and p1/p6 cleavage sites of Gag, both in vitro and in vivo. Cleavages at these sites have been shown to be rate limiting steps for polyprotein processing and viral maturation. Furthermore, these sites show significant sequence polymorphism, which also may have an impact on virion infectivity. We have studied the hydrolysis of oligopeptides representing these cleavage sites with representative mutations found as natural variations or that arise as resistant mutations. Wild-type and five drug resistant PRs with mutations within or outside the substrate binding site were tested. While the natural variations showed either increased or decreased susceptibility of peptides toward the proteinases, the resistant mutations always had a beneficial effect on catalytic efficiency. Comparison of the specificity changes obtained for the various substrates suggested that the maximization of the van der Waals contacts between substrate and PR is the major determinant of specificity: the same effect is crucial for inhibitor potency. The natural nucleocapsid/p1 and p1/p6 sites do not appear to be optimized for rapid hydrolysis. Hence, mutation of these rate limiting cleavage sites can partly compensate for the reduced catalytic activity of drug resistant mutant HIV-1 proteinases.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 269 : 16 (2002), p. 4114-4120. -
További szerzők:Weber, Irene T. Bagossi Péter (1966-2011) (biokémikus, vegyész) Boross Péter (1972-) (biokémikus, vegyész) Mahalingam, Bhuvaneshwari Louis, John M. Copeland, Terry D. Torshin, Ivan Y. Harrison, Robert W. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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6.

001-es BibID:BIBFORM040659
Első szerző:Fenyőfalvi György
Cím:Expression and characterization of human foamy virus proteinase / Fenyöfalvi György, Bagossi Péter, Copeland Terry D., Oroszlan Stephen, Boross Péter, Tözsér József
Dátum:1999
ISSN:0014-5793
Megjegyzések:The human foamy virus proteinase was expressed in fusion with maltose binding protein in Escherichia coli and purified. The specific activity of the fusion protein was similar to that of the processed enzyme. The kinetic constants on foamy virus cleavage site substrates were very low but comparable to those obtained with the gag-encoded avian proteinase on its own substrates. The proteinase showed preference for high ionic strength and a pH optimum of 6.6. None of the tested retroviral cleavage site peptides were substrates, however, some peptides representing cleavage sites in retrotransposons were properly processed by the enzyme
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Febs Letters. - 462 : 3 (1999), p. 397-401. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Copeland, Terry D. Oroszlan, Stephen Boross Péter (1972-) (biokémikus, vegyész) Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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7.

001-es BibID:BIBFORM040661
Első szerző:Kapust, Rachel B.
Cím:The P1' specificity of tobacco etch virus protease / Kapust Rachel B., Tözsér József, Copeland Terry D., Waugh David S.
Dátum:2002
ISSN:0006-291X
Megjegyzések:Affinity tags have become indispensable tools for protein expression and purification. Yet, because they have the potential to interfere with structural and functional studies, it is usually desirable to remove them from the target protein. The stringent sequence specificity of the tobacco etch virus (TEV) protease has made it a useful reagent for this purpose. However, a potential limitation of TEV protease is that it is believed to require a Gly or Ser residue in the P1' position of its substrates to process them with reasonable efficiency. Consequently, after an N-terminal affinity tag is removed by TEV protease, the target protein will usually retain a non-native Ser or Gly residue on its N-terminus, and in some cases this may affect its biological activity. To investigate the stringency of the requirement for Gly or Ser in the P1' position of a TEV protease recognition site, we constructed 20 variants of a fusion protein substrate with an otherwise optimal recognition site, each containing a different amino acid in the P1' position. The efficiency with which these fusion proteins were processed by TEV protease was compared both in vivo and in vitro. Additionally, the kinetic parameters K(M) and k(cat) were determined for a representative set of peptide substrates with amino acid substitutions in the P1' position. The results indicate that many side-chains can be accommodated in the P1' position of a TEV protease recognition site with little impact on the efficiency of processing.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochemical And Biophysical Research Communications. - 294 : 5 (2002), p. 949-955. -
További szerzők:Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Copeland, Terry D. Waugh, David S.
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8.

001-es BibID:BIBFORM040662
Első szerző:Kapust, Rachel B.
Cím:Tobacco etch virus protease : mechanism of autolysis and rational design of stable mutants with wild-type catalytic proficiency / Kapust, R. B., Tozser, J., Fox, J. D., Anderson, D. E., Cherry, S., Copeland, T. D., Waugh, D. S.
Dátum:2001
ISSN:1741-0126
Megjegyzések:Because of its stringent sequence specificity, the catalytic domain of the nuclear inclusion protease from tobacco etch virus (TEV) is a useful reagent for cleaving genetically engineered fusion proteins. However, a serious drawback of TEV protease is that it readily cleaves itself at a specific site to generate a truncated enzyme with greatly diminished activity. The rate of autoinactivation is proportional to the concentration of TEV protease, implying a bimolecular reaction mechanism. Yet, a catalytically active protease was unable to convert a catalytically inactive protease into the truncated form. Adding increasing concentrations of the catalytically inactive protease to a fixed amount of the wild-type enzyme accelerated its rate of autoinactivation. Taken together, these results suggest that autoinactivation of TEV protease may be an intramolecular reaction that is facilitated by an allosteric interaction between protease molecules. In an effort to create a more stable protease, we made amino acid substitutions in the P2 and P1' positions of the internal cleavage site and assessed their impact on the enzyme's stability and catalytic activity. One of the P1' mutants, S219V, was not only far more stable than the wild-type protease (approximately 100-fold), but also a more efficient catalyst.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Protein Engineering Design & Selection. - 14 : 12 (2001), p. 993-1000. -
További szerzők:Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Fox, Jeffrey D. Anderson, D. Eric Cherry, Scott Copeland, Terry D. Waugh, David S.
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9.

001-es BibID:BIBFORM040675
Első szerző:Nallamsetty, Sreedevi
Cím:Efficient site-specific processing of fusion proteins by tobacco vein mottling virus protease in vivo and in vitro / Nallamsetty Sreedevi, Kapust Rachel B., Tözsér József, Cherry Scott, Tropea Joseph E., Copeland Terry D., Waugh David S.
Dátum:2004
ISSN:1046-5928
Megjegyzések:Affinity tags are widely used as vehicles for the production of recombinant proteins. Yet, because of concerns about their potential to interfere with the activity or structure of proteins, it is almost always desirable to remove them from the target protein. The proteases that are most often used to cleave fusion proteins are factor Xa, enterokinase, and thrombin, yet the literature is replete with reports of fusion proteins that were cleaved by these proteases at locations other than the designed site. It is becoming increasingly evident that certain viral proteases have more stringent sequence specificity. These proteases adopt a trypsin-like fold but possess an unconventional catalytic triad in which Cys replaces Ser. The tobacco etch virus (TEV) protease is the best-characterized enzyme of this type. TEV protease cleaves the sequence ENLYFQG/S between QG or QS with high specificity. The tobacco vein mottling virus (TVMV) protease is a close relative of TEV protease with a distinct sequence specificity (ETVRFQG/S). We show that, like TEV protease, TVMV protease can be used to cleave fusion proteins with high specificity in vitro and in vivo. We compared the catalytic activity of the two enzymes as a function of temperature and ionic strength, using an MBP-NusG fusion protein as a model substrate. The behavior of TVMV protease was very similar to that of TEV protease. Its catalytic activity was greatest in the absence of NaCl, but diminished only threefold with increasing salt up to 200 mM. We found that the optimum temperatures of the two enzymes are nearly the same and that they differ only two-fold in catalytic efficiency, both at room temperature and 4 degrees C. Hence, TVMV protease may be a useful alternative to TEV protease when a recombinant protein happens to contain a sequence that is similar to a TEV protease recognition site or for protein expression strategies that involve the use of more than one protease.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Protein Expression And Purification. - 38 : 1 (2004), p. 108-115. -
További szerzők:Kapust, Rachel B. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész) Cherry, Scott Tropea, Joseph E. Copeland, Terry D. Waugh, David S.
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10.

001-es BibID:BIBFORM046523
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Effect of caspase cleavage-site phosphorylation on proteolysis / József Tőzsér, Péter Bagossi, Gábor Zahuczky, Suzanne I. Specht, Eva Majoreva, Terry D. Copeland
Dátum:2003
ISSN:0264-6021
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochemical Journal. - 372 : 1 (2003), p. 137-143. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Zahuczky Gábor (1975-) (molekuláris biológus, biokémikus, vegyész) Specht, Suzanne I. Majoreva, Eva Copeland, Terry D.
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11.

001-es BibID:BIBFORM040694
035-os BibID:PMID:2015912
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Comparison of the HIV-1 and HIV-2 proteinases using oligopeptide substrates representing cleavage sites in Gag and Gag-Pol polyproteins / József Tőzsér, Ivo Bláha, Terry D. Copeland, Ewald M. Wondrak, Stephen Oroszlan
Dátum:1991
ISSN:0014-5793
Megjegyzések:The substrate specificity of the human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) proteinases was compared using oligopeptides corresponding to cleavage sites in the Gag and Gag-Pol polyproteins of both viruses. All peptides mimicking cleavage sites at the junction of major functional protein domains were correctly cleaved by both enzymes. However, some other peptides thought to represent secondary cleavage sites remained intact. The kinetic parameters (Km and kcat) obtained for the different substrates showed several hundred-fold variation but were similar for the same substrate.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
külföldön készült közlemény
Megjelenés:Febs Letters. - 281 : 1-2 (1991), p. 77-80. -
További szerzők:Bláha, Ivo Copeland, Terry D. Wondrak, Ewald M. Oroszlan, Stephen
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12.

001-es BibID:BIBFORM040684
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Kinetic and modeling studies of S3-S3' subsites of HIV proteinases / Tözsér J., Weber I. T., Gustchina A., Bláha I., Copeland T. D., Louis J. M., Oroszlan S.
Dátum:1992
ISSN:0006-2960
Megjegyzések:Kinetic analysis and modeling studies of HIV-1 and HIV-2 proteinases were carried out using the oligopeptide substrate [formula: see text] and its analogs containing single amino acid substitutions in P3-P3' positions. The two proteinases acted similarly on the substrates except those having certain hydrophobic amino acids at P2, P1, P2', and P3' positions (Ala, Leu, Met, Phe). Various amino acids seemed to be acceptable at P3 and P3' positions, while the P2 and P2' positions seemed to be more restrictive. Polar uncharged residues resulted in relatively good binding at P3 and P2 positions, while at P2' and P3' positions they gave very high Km values, indicating substantial differences in the respective S and S' subsites of the enzyme. Lys prevented substrate hydrolysis at any of the P2-P2' positions. The large differences for subsite preference at P2 and P2' positions seem to be at least partially due to the different internal interactions of P2 residue with P1', and P2' residue with P1. As expected on the basis of amino acid frequency in the naturally occurring cleavage sites, hydrophobic residues at P1 position resulted in cleavable peptides, while polar and beta-branched amino acids prevented hydrolysis. On the other hand, changing the P1' Pro to other amino acids prevented substrate hydrolysis, even if the substituted amino acid had produced a good substrate in other oligopeptides representing naturally occurring cleavage sites. The results suggest that the subsite specificity of the HIV proteinases may strongly depend on the sequence context of the substrate.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochemistry. - 31 : 20 (1992), p. 4793-4800. -
További szerzők:Weber, Irene T. Gustchina, Alla Bláha, Ivo Copeland, Terry D. Louis, John M. Oroszlan, Stephen
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