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1.

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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2.

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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3.

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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4.

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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5.

001-es BibID:BIBFORM040699
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Comparative studies on the substrate specificity of avian myeloblastosis virus proteinase and lentiviral proteinases / Tözsér J., Bagossi P., Weber I. T., Copeland T. D., Oroszlan S.
Dátum:1996
Megjegyzések:The retroviral proteinase (PR) seems to play crucial roles in the viral life cycle, therefore it is an attractive target for chemotherapy. Previously we studied the specificity of human immunodeficiency virus (HIV) type 1 and type 2 as well as equine infectious anemia virus PRs using oligopeptide substrates. Here a similar approach is used to characterize the specificity of avian myeloblastosis virus (AMV) PR and to compare it with those of the previously characterized lentiviral PRs. All peptides representing naturally occurring Gag and Gag-Pol cleavage sites were substrates of the AMV PR. Only half of these peptides were substrates of HIV-1 PR. The Km values for AMV PR were in a micromolar range previously found for the lentiviral PRs; however, the kcat values were in a 10 30-fold lower range. A series of peptides containing single amino acid substitutions in a sequence representing a naturally occurring HIV cleavage site was used to characterize the seven substrate binding subsites of the AMV PR. The largest differences were found at the P4 and P2 positions of the substrate. Detailed analysis of the results by molecular modeling and comparison with previously reported data revealed the common characteristics of the specificity of the retroviral PRs as well as its strong dependence on the sequence context of the substrate.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:The Journal of biological chemistry. - 271 : 12 (1996), p. 6781-6788. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Weber, Irene T. Copeland, Terry D. Oroszlan, Stephen
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6.

001-es BibID:BIBFORM040701
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Studies on the Symmetry and Sequence Context Dependence of the HIV-1 Proteinase Specificity / Tözsér J., Bagossi P., Weber I. T., Louis J. M., Copeland T. D., Oroszlan S.
Dátum:1997
ISSN:0021-9258
Megjegyzések:Two major types of cleavage sites with different sequence preferences have been proposed for the human immunodeficiency virus type 1 (HIV-1) proteinase. To understand the nature of these sequence preferences better, single and multiple amino acid substitutions were introduced into a type 1 cleavage site peptide, thus changing it to a naturally occurring type 2 cleavage site sequence. Our results indicated that the previous classification of the retroviral cleavage sites may not be generally valid and that the preference for a residue at a particular position in the substrate depends strongly on the neighboring residues, including both those at the same side and at the opposite side of the peptide backbone of the substrate. Based on these results, pseudosymmetric (palindromic) substrates were designed. The retroviral proteinases are symmetrical dimers of two identical subunits; however, the residues of naturally occurring cleavage sites do not show symmetrical arrangements, and no obvious symmetrical substrate preference has been observed for the specificity of HIV proteinase. To examine the role of the asymmetry created by the peptide bonds on the specificity of the respective primed and nonprimed halves of the binding site, amino acid substitutions were introduced into a palindromic sequence. In general, the results suggested that the asymmetry does not result in substantial differences in specificity of the S3 and S3' subsites, whereas its effect is more pronounced for the S2 and S2' subsites. Although it was possible to design several good palindromic substrates, asymmetrical arrangements may be preferred by the HIV proteinase.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal Of Biological Chemistry. - 272 : 27 (1997), p. 16807-16814. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Weber, Irene T. Louis, John M. Copeland, Terry D. Oroszlan, Stephen
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7.

001-es BibID:BIBFORM040690
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Effect of serine and tyrosine phosphorylation on retroviral proteinase substrates / Tozser Jozsef, Bagossi Peter, Boross Peter, Louis John M., Majerova Eva, Oroszlan Stephen, Copeland Terry D.
Dátum:1999
ISSN:0014-2956
Megjegyzések:Vimentin, a cellular substrate of HIV type 1 (HIV-1) proteinase, contains a protein kinase C (PKC) phosphorylation site at one of its cleavage sites. Peptides representing this site were synthesized in P2 Ser-phosphorylated and nonphosphorylated forms. While the nonphosphorylated peptide was a fairly good substrate of the enzyme, phosphorylation prevented hydrolysis. Phosphorylation of human recombinant vimentin by PKC prevented its processing within the head domain, where the phosphorylation occurred. Oligopeptides representing naturally occurring cleavage sites at the C-terminus of the Rous sarcoma virus integrase were assayed as substrates of the avian proteinase. Unlike the nonphosphorylated peptides, a Ser-phosphorylated peptide was not hydrolyzed by the enzyme at the Ser-Pro bond, suggesting the role of previously established phosphorylation in processing at this site. Ser-phosphorylated and Tyr-phosphorylated forms of model substrates were also tested as substrates of the HIV-1 and the avian retroviral proteinases. In contrast to the moderate effect of P4 Ser phosphorylation, phosphorylation of P1 Tyr prevented substrate hydrolysis by HIV-1 proteinase. Substrate phosphorylation had substantially smaller effects on the hydrolysis by the avian retroviral proteinase. As the active retroviral proteinase as well as various protein kinases are incorporated into mature virions, substrate phosphorylation resulting in attenuation or prevention of proteolytic processing may have important consequences in the regulation of the retroviral life cycle as well as in virus-host cell interactions.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 265 : 1 (1999), p. 423-429. -
További szerzők:Bagossi Péter (1966-2011) (biokémikus, vegyész) Boross Péter (1972-) (biokémikus, vegyész) Louis, John M. Majerova, Eva Oroszlan, Stephen Copeland, Terry D.
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8.

001-es BibID:BIBFORM040704
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Human immunodeficiency virus type 1 capsid protein is a substrate of the retroviral proteinase while integrase is resistant toward proteolysis / Tözsér József, Shulenin Sergey, Kádas János, Boross Péter, Bagossi Péter, Copeland Terry D., Nair Bala C., Sarngadharan Mangalasseril G., Oroszlan Stephen
Dátum:2003
ISSN:0042-6822
Megjegyzések:The capsid protein of human immunodeficiency virus type 1 was observed to undergo proteolytic cleavage in vitro when viral lysate was incubated in the presence of dithiothreitol at acidic pH. Purified HIV-1 capsid protein was also found to be a substrate of the viral proteinase in a pH-dependent manner; acidic pH (<7) was necessary for cleavage, and decreasing the pH toward 4 increased the degree of processing. Based on N-terminal sequencing of the cleavage products, the capsid protein was found to be cleaved at two sites, between residues 77 and 78 as well as between residues 189 and 190. Oligopeptides representing these cleavage sites were also cleaved at the expected peptide bonds. The presence of cyclophilin A decreased the degree of capsid protein processing. Unlike the capsid protein, integrase was found to be resistant toward proteolysis in good agreement with its presence in the preintegration complex.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Virology. - 310 : 1 (2003), p. 16-23. -
További szerzők:Shulenin, Sergey Kádas János (1976-) (molekuláris biológus, biokémikus, kertészmérnök) Boross Péter (1972-) (biokémikus, vegyész) Bagossi Péter (1966-2011) (biokémikus, vegyész) Copeland, Terry D. Nair, Bala C. Sarngadharan, Mangalasseril G. Oroszlan, Stephen
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9.

001-es BibID:BIBFORM040692
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Comparison of the substrate specificity of two potyvirus proteases / Tözsér József, Tropea Joseph E., Cherry Scott, Bagossi Peter, Copeland Terry D., Wlodawer Alexander, Waugh David S.
Dátum:2005
ISSN:1742-464X
Megjegyzések:The substrate specificity of the nuclear inclusion protein a (NIa) proteolytic enzymes from two potyviruses, the tobacco etch virus (TEV) and tobacco vein mottling virus (TVMV), was compared using oligopeptide substrates. Mutations were introduced into TEV protease in an effort to identify key determinants of substrate specificity. The specificity of the mutant enzymes was assessed by using peptides with complementary substitutions. The crystal structure of TEV protease and a homology model of TVMV protease were used to interpret the kinetic data. A comparison of the two structures and the experimental data suggested that the differences in the specificity of the two enzymes may be mainly due to the variation in their S4 and S3 binding subsites. Two key residues predicted to be important for these differences were replaced in TEV protease with the corresponding residues of TVMV protease. Kinetic analyses of the mutants confirmed that these residues play a role in the specificity of the two enzymes. Additional residues in the substrate-binding subsites of TEV protease were also mutated in an effort to alter the specificity of the enzyme.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Febs Journal. - 272 : 2 (2005), p. 514-523. -
További szerzők:Tropea, Joseph E. Cherry, Scott Bagossi Péter (1966-2011) (biokémikus, vegyész) Copeland, Terry D. Wlodawer, Alexander Waugh, David S.
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10.

001-es BibID:BIBFORM040126
Első szerző:Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:Comparison of the substrate specificity of the human T-cell leukemia virus and human immunodeficiency virus proteinases / József Tőzsér, Gábor Zahuczky, Péter Bagossi, John M. Louis, Terry D. Copeland, Stephen Oroszlan, Robert W. Harrison, Irene T. Weber
Dátum:2000
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal of Biochemistry. - 267 : 20 (2000), p. 6287-6295. -
További szerzők:Zahuczky Gábor (1975-) (molekuláris biológus, biokémikus, vegyész) Bagossi Péter (1966-2011) (biokémikus, vegyész) Louis, John M. Copeland, Terry D. Oroszlan, Stephen Harrison, Robert W. Weber, Irene T.
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11.

001-es BibID:BIBFORM039225
Első szerző:Zahuczky Gábor (molekuláris biológus, biokémikus, vegyész)
Cím:Cloning of the bovine leukemia virus proteinase in Escherichia coli and comparison of its specificity to that of human T-cell leukemia virus proteinase / Gábor Zahuczky, Péter Boross, Péter Bagossi, Gabriella Emri, Terry D. Copeland, Stephen Oroszlan, John M. Louis, József Tőzsér
Dátum:2000
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Biochimica et Biophysica Acta (BBA). Protein Structure and Molecular Enzymology. - 1478 : 1 (2000), p. 1-8. -
További szerzők:Boross Péter (1972-) (biokémikus, vegyész) Bagossi Péter (1966-2011) (biokémikus, vegyész) Emri Gabriella (1972-) (bőrgyógyász, allergológus, onkológus) Copeland, Terry D. Oroszlan, Stephen Louis, John M. Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
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