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001-es BibID:	BIBFORM040645
Első szerző:	Bagossi Péter (biokémikus, vegyész)
Cím:	Comparison of the specificity of homo- and heterodimeric linked HIV-1 and HIV-2 proteinase dimers / Bagossi, P., Cheng, Y. S., Oroszlan, S., Tozser, J.
Dátum:	1998
ISSN:	1741-0126
Megjegyzések:	The specificity of linked homo- and heterodimeric HIV-1 and HIV-2 proteinases was characterized by using oligopeptide substrates. For two substrates the k(cat)/Km values for the heterodimers were the mean values for those of the homodimers, suggesting that these substrates could productively bind into the heterodimers in both directions. However, for two other substrates the k(cat)/Km values for the heterodimers were higher than those of the homodimers, suggesting that these substrates could productively bind into the enzymes in a preferable direction. However, the mode of binding does not seem to depend on the sequential position of the subunits. The studied linked homo- and heterodimers may represent intermediate stages in the evolution of bilobal aspartic proteinases. As divergence in sequence of the two halves of such a proteinase increases, the possibility of bidirectional binding is likely lost at the expense of the optimized side-chain subsite interactions. The differences in observed and calculated k(cat)/Km values revealed dependence of the substrate specificity at one subsite of the enzyme from the next residue in sequence of substrate. These findings were also supported by molecular modeling studies.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Protein Engineering Design & Selection. - 11 : 6 (1998), p. 439-445. -
További szerzők:	Cheng, Yin-Shyun E. Oroszlan, Stephen Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM040634
Első szerző:	Bagossi Péter (biokémikus, vegyész)
Cím:	Activity of linked HIV-1 proteinase dimers containing mutations in the active site region / Bagossi Péter, Cheng Yin-Shyun E., Oroszlan Stephen, Tözsér József
Dátum:	1996
ISSN:	1741-0126
Megjegyzések:	Mutations were introduced into the active site triplet (Asp-Thr-Gly) of one or both subunits of a linked dimer of human immunodeficiency virus type 1 proteinase. Mutation of Thr to Ser in one or both subunits did not alter the activity of the enzyme substantially, whereas its mutation to Asn in one subunit caused a dramatic decrease in catalytic efficiency. Mutation of Gly to Val in one subunit also yielded an enzyme with very low activity. The enzymes containing Thr-->Asn and Gly-->Val mutations in both subunits resulted in inactive enzymes, based on their inability to self-process and on assay with an oligopeptide substrate. The dramatic decrease in enzyme efficiency of the mutants was interpreted using molecular models of the enzymes.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Protein Engineering Design & Selection. - 9 : 11 (1996), p. 997-1003. -
További szerzők:	Cheng, Yin-Shyun E. Oroszlan, Stephen Tőzsér József (1959-) (molekuláris biológus, biokémikus, vegyész)
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM040689
Első szerző:	Tőzsér József (molekuláris biológus, biokémikus, vegyész)
Cím:	Activity of Tethered Human Immunodeficiency Virus 1 Protease Containing Mutations in the Flap Region of One Subunit / Tozser Jozsef, Yin Fay H., Cheng Yin-Shyun E., Bagossi Peter, Weber Irene T., Harrison Robert W., Oroszlan Stephen
Dátum:	1997
ISSN:	0014-2956
Megjegyzések:	The tethered-dimer protease of human immunodeficiency virus 1 (HIV-1) [Cheng Y.-S. E., Yin, F.H., Foundling, S., Blomstrom, D. & Kettner, C. A. (1990) Proc. Natl Acad. Sci. USA 87, 9660-9664] and its mutants containing amino acid substitutions or deletions or both in only one flap region were expressed in Escherichia coli. These mutant enzymes showed various degrees of self-processing and significantly reduced catalytic activity toward oligopeptide substrates compared with the wild type. Kinetic parameters determined for one of the oligopeptide substrates showed a dramatic increase in K(m) and decrease in Kcat values. Unexpectedly, the substrate cleavage was more efficient in low salt concentration for a mutant containing a shortened hydrophilic flap. Assays with oligopeptides representing naturally occurring cleavage sites or oligopeptides containing single amino acid substitutions at the P2 and P2' substrate positions showed only moderate changes in the substrate specificity of the mutant proteases. Predicted structures for the mutants were constructed by molecular modeling and used to interpret the results of kinetic measurements. In general, the data suggest that the mutated part of the flaps does not have a major role in determining substrate specificity; rather, it provides the hydrophobic environment and hydrogen-bond interactions with the conserved water that are necessary for efficient substrate binding and catalysis.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	European Journal Of Biochemistry 244 : 1 (1997), p. 235-241. -
További szerzők:	Yin, Fay H. Cheng, Yin-Shyun E. Bagossi Péter (1966-2011) (biokémikus, vegyész) Weber, Irene T. Harrison, Robert W. Oroszlan, Stephen
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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