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1.

001-es BibID:BIBFORM005936
Első szerző:Damjanovich Sándor (biofizikus)
Cím:The role of the allosteric sites in the x-ray inactivation of phosphorylase b / Damjanovich, S., Sanner, T., Pihl, A.
Dátum:1967
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Binding Sites
Chloromercuribenzoates
Glucosyltransferases
pharmacology
Phosphorylase b
radiation effects
Sulfhydryl Compounds
Megjelenés:European Journal of Biochemistry. - 1 : 3 (1967), p. 347-352. -
További szerzők:Sanner, Tore Pihl, Alexander
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elektronikus változat
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2.

001-es BibID:BIBFORM005929
Első szerző:Damjanovich Sándor (biofizikus)
Cím:The functional and fluorescence properties of Escherichia coli RNA polymerase reacted with fluorescamine / Damjanovich, S., Bahr, W., Jovin, T. M.
Dátum:1977
Megjegyzések:Fluorescamine (4-phenylspiro[furan-2,(3)1'-phthalan]-3,3'-dione) reacts rapidly with Escherichia coli RNA polymerase and produces a fluorescent derivative which is inactivated to an extent dependent upon reagent concentration. Excess fluorescamine is rapidly hydrolysed. Reaction is with xi-amino gruops of lysine residues in all subunits as revealed by gel electrophoresis and fluorescence scanning. 2. The extent of inactivation and fluorescence yield are diminished in the presence of added template, a finding which provides evidence for the existence of reactive and essential amino groups which can be at least partially shielded by DNA in the binary complexes. The relative decrease of fluorescence is greatest in the betabeta' subunits. Holoenzyme and core enzyme show essentially the same behavior. 3. The inactivation of activity by fluorescamine is primarily at the level of initiation. Template binding and chain propagation are less affected. 4. The enzyme derivatized by fluorescamine shows an intense fluorescence with a peak at 490 nm and an excitation maximum at 390 nm. The fluorescence lifetime is in the range of 3-8 ns and the emission is highly polarized. In reactions carried out at high ionic strength the fluorescence yield is approximately double that at low ionic strength and insensitive to the presence of template. 5. Energy transfer is observed between the derivatized enzyme as donor and ethidium bromide as acceptor in the presence of template to which both the enzyme and intercalating dye are bound. The transfer efficiency is a function of the relative concentrations and of the conditions of reaction with fluorescamine. An average transfer distance of approx. 4-5 nm has been calculated suggesting a close proximity between bound polymerase and helical regions of the template.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Binding Sites
Dna
DNA-Directed RNA Polymerase
Energy Transfer
enzymology
Escherichia coli
Ethidium
Fluorescamine
Fluorescence
Kinetics
Lysine
metabolism
pharmacology
Protein Binding
Protein Conformation
Spectrometry, Fluorescence
Spiro Compounds
Megjelenés:European Journal of Biochemistry. - 72 : 3 (1977), p. 559-569. -
További szerzők:Bahr, W. Jovin, Thomas M.
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elektronikus változat
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3.

001-es BibID:BIBFORM003923
Első szerző:Damjanovich Sándor (biofizikus)
Cím:The Role of the allosteric sites in the X-ray inactivation of phosphorylase b / S. Damjanovich, T. Sanner, A. Pihl
Dátum:1967
Megjegyzések:Crystalline rabbit muscle phosphorylase b was irradiated in dilute aqueous solution with X-rays. The enzyme was inactivated with a G-value of 0.09. Measurements of the K<sub>m</sub> values of the substrate, glucose-1-phosphate, and the allosteric activator, adenosine-5'-phosphate, demonstrated that these increased linearly with increasing radiation dose. The effect on the K<sub>m</sub> for the activator was 4 times greater than that on the K<sub>m</sub> for the substrate. The data indicate that the allosteric function is more sensitive to inactivation than the catalytic function. The enzyme SH-groups were destroyed by X-rays with a G-value of 1.8. Comparison with data on the inactivation of the enzyme by sulfhydryl blocking agents demonstrated that the X-ray destruction of sulfhydryl groups was sufficiently large to account for the X-ray inactivation of the enzyme. Blocking of two SH-groups with pCMB reduced the radiosensitivity of the enzyme by a factor of 2. Measurement of the K<sub>m</sub> values showed that the pCMB blocking protected preferentially the allosteric sites. The data indicate that the inactivation of phosphorylase b, both by sulfhydryl agents and by X-rays, involves largely an effect on the allosteric sites with loss of ability to bind the essential activator and consequent loss of ability to bind substrate.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Allosteric regulation
X-rays
Irradiation
Enzyme inhibitors
Phosphorylase
Allosteric enzymes
Megjelenés:European Journal of Biochemistry. - 1 : 3 (1967), p. 347-352. -
További szerzők:Sanner, Tore Pihl, Alexander
Internet cím:elektronikus változat
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4.

001-es BibID:BIBFORM039166
035-os BibID:(scopus)0036272752 (wos)000175906900005
Első szerző:Goda Katalin (biofizikus)
Cím:Effects of ATP depletion and phosphate analogues on P-glycoprotein conformation in live cells / Goda, K., Nagy, H., Mechetner, E., Cianfriglia, M., Szabo, G.
Dátum:2002
ISSN:0014-2956
Megjegyzések:P-glycoprotein (Pgp), a membrane pump often responsible for the multidrug resistance of cancer cells, undergoes conformational changes in the presence of substrates/modulators, or upon ATP depletion, reflected by its enhanced reactivity with the UIC2 monoclonal antibody. When the UIC2-shift was elicited by certain modulators (e.g. cyclosporin A or vinblastine, but not with verapamil or Tween 80), the subsequent binding of other monoclonal anti-Pgp Ig sharing epitopes with UIC2 (e.g. MM12.10) was abolished [Nagy, H., Goda, K., Arceci, R., Cianfriglia, M., Mechetner, E. & Szabó Jr, G. (2001) Eur. J. Biochem.268, 2416?2420]. To further study the relationship between UIC2-shift and the suppression of MM12.10 binding, we compared, on live cells, how ATP depletion and treatment of cells with phosphate analogues (sodium orthovanadate, beryllium fluoride and fluoro-aluminate) that trap nucleotides at the catalytic site, affect the two phenomena. Similarly to modulators or ATP depleting agents, all the phosphate analogues increased daunorubicin accumulation in Pgp-expressing cells. Prelabeling of ATP depleted cells with UIC2 completely abolished the subsequent binding of MM12.10, in accordance with the enhanced binding of the first mAb. Vanadate and beryllium fluoride, but not fluoro-aluminate, reversed the effect of cyclosporin A, preventing UIC2 binding and allowing for labeling of cells with MM12.10. Thus, changes in UIC2 reactivity are accompanied by complementary changes in MM12.10 binding also in response to direct modulation of the ATP-binding site, confirming that conformational changes intrinsic to the catalytic cycle are reflected by both UIC2-related phenomena. These data also fit a model where the UIC2 epitope is available for antibody binding throughout the catalytic cycle including the step of ATP binding, to become unavailable only in the catalytic transition state.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:European Journal Of Biochemistry. - 269 : 11 (2002), p. 2672-2677. -
További szerzők:Nagy Henrietta Mechetner, Eugene Cianfriglia, Maurizio Szabó Gábor (1953-) (biofizikus)
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DOI
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5.

001-es BibID:BIBFORM039514
Első szerző:Matkó János (biológus)
Cím:GPI-microdomains (membrane rafts) and signaling of the multi-chain interleukin-2 receptor in human lymphoma/leukemia T cell lines / Matko, J., Bodnar, A., Vereb, G., Bene, L., Vamosi, G., Szentesi, G., Szollosi, J., Gaspar, R., Horejsi, V., Waldmann, T. A., Damjanovich, S.
Dátum:2002
ISSN:0014-2956
Megjegyzések:Subunits (alpha, beta and gamma) of the interleukin-2 receptor complex (IL-2R) are involved in both proliferative and activation-induced cell death (AICD) signaling of T cells. In addition, the signaling beta and gamma chains are shared by other cytokines (e.g. IL-7, IL-9, IL-15). However, the molecular mechanisms responsible for recruiting/sorting the alpha chains to the signaling chains at the cell surface are not clear. Here we show, in four cell lines of human adult T cell lymphoma/leukemia origin, that the three IL-2R subunits are compartmented together with HLA glycoproteins and CD48 molecules in the plasma membrane, by means of fluorescence resonance energy transfer (FRET), confocal microscopy and immuno-biochemical techniques. In addition to the beta and gamma(c) chains constitutively expressed in detergent-resistant membrane fractions (DRMs) of T cells, IL-2Ralpha (CD25) was also found in DRMs, independently of its ligand-occupation. Association of CD25 with rafts was also confirmed by its colocalization with GM-1 ganglioside. Depletion of membrane cholesterol using methyl-beta-cyclodextrin substantially reduced co-clustering of CD25 with CD48 and HLA-DR, as well as the IL-2 stimulated tyrosine-phosphorylation of STATs (signal transducer and activator of transcription). These data indicate a GPI-microdomain (raft)-assisted recruitment of CD25 to the vicinity of the signaling beta and gamma(c) chains. Rafts may promote rapid formation of a high affinity IL-2R complex, even at low levels of IL-2 stimulus, and may also form a platform for the regulation of IL-2 induced signals by GPI-proteins (e.g. CD48). Based on these data, the integrity of these GPI-microdomains seems critical in signal transduction through the IL-2R complex.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:European Journal Of Biochemistry. - 269 : 4 (2002), p. 1199-1208. -
További szerzők:Dóczy-Bodnár Andrea (1970-) (biofizikus) Vereb György (1965-) (biofizikus, orvos) Bene László (1963-) (biofizikus) Vámosi György (1967-) (biofizikus) Szentesi Gergely (1976-) (kémia-fizika tanár) Szöllősi János (1953-) (biofizikus) Gáspár Rezső (1944-) (biofizikus) Horejsi, Václav Waldmann, Thomas A. Damjanovich Sándor (1936-2017) (biofizikus)
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DOI
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6.

001-es BibID:BIBFORM040018
Első szerző:Nagy Henrietta
Cím:P-Glycoprotein conformational changes detected by antibody competition / Nagy Henrietta, Goda Katalin, Arceci Robert, Cianfriglia Maurizio, Mechetner Eugene, Szabó Gábor jr.
Dátum:2001
ISSN:0014-2956
Megjegyzések:Conformational changes accompanying P-glycoprotein (Pgp) mediated drug transport are reflected by changes in the avidity of certain monoclonal antibodies (mAbs). More of the UIC2 mAb binds to Pgp-expressing cells in the presence of substrates or modulators [Mechetner, E.B., Schott, B., Morse, S.B., Stein, W., Druley, T., Dvis, K.A., Tsuruo, T. & Roninson, I.B. (1997) Proc. Natl Acad. Sci. USA 94, 12908-12913], while the binding of other mAbs (e.g. MM12.10, MRK16, 4E3) is not conformation sensitive. Pre-staining of Pgp+ cells with UIC2 decreased the subsequent binding of MM12.10 mAb by about 30-40%, suggesting that there are Pgp molecules available for both UIC2 and MM12.10, and others accessible only for MM12.10. In the presence of certain substrates/modulators such as vinblastin, cyclosporin A or valinomycin, the MM12.10 reactivity was completely abolished by preincubation with UIC2. However, verapamil, Tween-80 and nifedipine did not influence the ratio of bound mAbs significantly. This is the first assay to our knowledge, sharply distinguishing two classes of modulators. The conformational changes accompanying the mAb competition phenomenon appear to be closely related, though not identical to those accompanying the UIC2-shift, as suggested by the simultaneous assessment of the two phenomena.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
3T3 Cells
Animal
Antibiotics
Antibiotics,Peptide
Antibodies
Antibodies,Monoclonal
Antineoplastic Agents
Antineoplastic Agents,Phytogenic
Binding,Competitive
Biophysics
Calcium
Calcium Channel Blockers
Cells
chemistry
Cyclosporine
Drug Resistance,Neoplasm
Enzyme Inhibitors
Flow Cytometry
Human
Hungary
metabolism
Mice
Nifedipine
P-Glycoprotein
pharmacology
Polysorbates
Protein Binding
Protein Conformation
Substrate Specificity
Support,Non-U.S.Gov't
Tumor Cells,Cultured
Valinomycin
Verapamil
Vinblastine
Megjelenés:European Journal Of Biochemistry. - 268 : 8 (2001), p. 2416-2420. -
További szerzők:Goda Katalin (1969-) (biofizikus) Arceci, Robert Cianfriglia, Maurizio Mechetner, Eugene Szabó Gábor (1980-) (orvos) jr
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DOI
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7.

001-es BibID:BIBFORM005989
035-os BibID:(scopus)0019558824
Első szerző:Pozsgay Marianne
Cím:Investigation of the substrate-binding site of trypsin by the aid of tripeptidyl-p-nitroanilide substrates / Marianne Pozsgay, Gábor Szabó, Sandor Bajusz, Roger Simonsson, Rezsö Gáspár, Pál Elődi
Dátum:1981
Megjegyzések:The kinetic parameters of the tryptic hydrolysis of tripeptidyl-p-nitroanilide substrates were determined and the data were studied by regression analysis. The sequence of substrates optimal from the viewpoint of kinetic constants 1/Km, kcat and kcat/Km was established and the influence of amino acid side chains on the binding and reactivity of substrates was calculated. At subsite P3 [notation of Schechter and Berger (1967) Biochem. Biophys, Res. Commun. 27, 157] polar side chains (Asn, D-Arg) are favourable as regards 1/Km, whereas hydrophobic side chains are preferred definitely from the viewpoint of catalytic efficiency, just as at subsite P2. In the side chain contributions, calculated for the kinetic parameters, the P3-S3 interaction predominates, in spite of the fact that the properties of the residue at subsite P1 decide whether hydrolysis occurs at all. The ZAsn-Ile-Arg-Nan sequence was predicted as a better substrate than those tested experimentally. The compound was synthesized, and the calculated value of its 1/Km (116.4 mM-1) was in a good agreement with the measured value (100.2 mM-1). Comparing the data obtained with trypsin with those observed with thrombin, elastase and subtilisin, we can establish that the homology of these enzymes can be characterized at each binding subsite by the aid of tripeptidyl-p-nitroanilide substrates. The quantities derived allow one to envisage a novel type of comparison of the proteases.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
analysis
Anilides
Animal
Binding Sites
Cattle
enzymology
Kinetics
metabolism
Pancreas
Peptides
Protein Binding
Structure-Activity Relationship
Substrate Specificity
Support,Non-U.S.Gov't
Trypsin
Megjelenés:European Journal of Biochemistry. - 115 : 3 (1981), p. 497-502. -
További szerzők:Szabó Gábor (1953-) (biofizikus) Bajusz Sándor Simonsson, Roger Gáspár Rezső (1944-) (biofizikus) Elődi Pál (1927-2002) (biokémikus)
Internet cím:DOI
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8.

001-es BibID:BIBFORM005988
Első szerző:Pozsgay Marianne
Cím:Study of the specificity of thrombin with tripeptidyl-p-nitroanilide substrates / Marianne Pozsgay, Gabriella Cs. Szabó, Pál Elődi, Rezsö Gáspár, Sandor Bajusz, Roger Simonsson
Dátum:1981
Megjegyzések:The kinetic behaviour of human thrombin has been studied with 26 tripeptidyl-p-nitroanilide substrates protected at the N terminus and with 9 unprotected ones. By the regression analysis of experimentally determined 1/Km, kcat and kcat/Km values the individual contribution of each side chain of the various substrates to the kinetic parameters was calculated. The contributions to the kinetic parameters of the best substrates provide information about the structure of the binding site. The interaction of subsites S1 and P1, which determines primary specificity, proved to be marginal on the basis of contribution values, though it depends upon this contact whether the substrate is hydrolyzed at all. At subsite S2 proline appeared to be favourable. Subsite S3 plays an important role in efficiency. The best parameters were obtained here with the D configurations of bulky amino acid residues. The aromatic protecting groups applied did not improve the properties of substrates. BZDPhe-Pro-Arg-Nan was predicted by calculation to be better than the protected substrates assayed. The compound was synthesized and tested. Its experimentally determined 1/Km, 55.1 mM-1, was in good agreement with 50.9 mM-1 found by calculation.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
analysis
Anilides
Human
Kinetics
metabolism
Peptides
Structure-Activity Relationship
Substrate Specificity
Support,Non-U.S.Gov't
Thrombin
Megjelenés:European Journal of Biochemistry. - 115 : 3 (1981), p. 491-495. -
További szerzők:Szabó Cs. Gabriella Elődi Pál (1927-2002) (biokémikus) Gáspár Rezső (1944-) (biofizikus) Bajusz Sándor Simonsson, Roger
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9.

001-es BibID:BIBFORM005947
Első szerző:Pozsgay Marianne
Cím:A method for designing peptide substrates for proteases. Tripeptidyl-p-nitroanilide substrates for subtilisin Carlsberg / Pozsgay, M., Gaspar, R., Bajusz, S., Elodi, P.
Dátum:1979
Megjegyzések:The kinetic parameters of 25 peptidyl-p-nitroanilide substrates were investigated with subtilisin Carlsberg as model enzyme. 2. For a series of 12 substrates, the contribution of various side chains to the affinity constant was computed by regression analysis. From these contributions the sequence of a new and better substrate, N-benzyloxycarbonyl-arginyl-norleucyl-norleucyl-p-nitroanilide (Z-Arg-Nle-Nle-Nan) was predicted. The compound was synthesized and assayed. Its calculated 1/Km value, 43.5 mM-1, was in a good agreement with the value of 40.0 mM-1 that was determined experimentally. 3. On expanding the series to 19 substrates, it was found that the productivity of enzyme-substrate binding is influenced primarily by those subsites which have a significantly greater contribution to the affinity constants than others. 4. The additivity principle applied reasonably well for the contribution of individual side chains to the kinetic parameters. This fact suggests that regression analysis can be used for the prediction of the amino acid sequence of better substrates than those already tested, probably not only for subtilisin but also for other proteolytic enzymes
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Amino Acid Sequence
analysis
Kinetics
metabolism
Oligopeptides
Regression Analysis
Substrate Specificity
Subtilisins
Megjelenés:European Journal of Biochemistry. - 95 : 1 (1979), p. 115-119. -
További szerzők:Gáspár Rezső (1944-) (biofizikus) Bajusz Sándor Elődi Pál (1927-2002) (biokémikus)
Internet cím:elektronikus változat
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