Kinetics of Nucleotide-Induced Changes in the Tryptophan Fluorescence of the Molecular Chaperone Hsc70 and Its Subfragments Suggest the ATP-Induced Conformational Change Follows Initial ATP Binding

Biochemistry ◽  
1995 ◽  
Vol 34 (36) ◽  
pp. 11635-11644 ◽  
Author(s):  
Jeung-Hoi Ha ◽  
David B. McKay
Keyword(s):  
Conformational Change ◽  
Molecular Chaperone ◽  
Tryptophan Fluorescence ◽  
Atp Binding ◽  
Induced Changes ◽  
Kinetics Of

scholarly journals Inactivation of sarcoplasmic-reticulum Ca2+-ATPase in low-frequency-stimulated muscle results from a modification of the active site

1992 ◽  
Vol 285 (1) ◽  
pp. 303-309 ◽  
Author(s):  
S Matsushita ◽  
D Pette
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Active Site ◽  
Low Frequency ◽  
Fluorescein Isothiocyanate ◽  
Tryptophan Fluorescence ◽  
Atp Binding ◽  
Binding Characteristics ◽  
Intrinsic Tryptophan Fluorescence ◽  
Inactive Form ◽  
Induced Changes

Molecular changes underlying the partial inactivation of the sarcoplasmic-reticulum (SR) Ca(2+-) ATPase in low-frequency-stimulated fast-twitch muscle were investigated in the present study. The specific Ca(2+)-ATPase activity, as well as the ATP- and acetyl phosphate-driven Ca2+ uptakes by the SR, were reduced by approx. 30% in 4-day-stimulated muscle. Phosphoprotein formation of the enzyme in the presence of ATP or Pi was also decreased to the same extent. Measurements of ATP binding revealed a 30% decrease in binding to the enzyme. These changes were accompanied by similar decreases in the ligand-induced (ATP, ADP, Pi) intrinsic tryptophan fluorescence. A decreased binding of fluorescein isothiocyanate (FITC) corresponded to the lower ATP binding and phosphorylation of the enzyme. Moreover, Pi-induced changes in fluorescence of the FITC-labelled enzyme did not differ between SR from stimulated and contralateral muscles, indicating that Ca(2+)- ATPase molecules which did not bind FITC were responsible for the decreased Pi-dependent phosphorylation, and therefore represented the inactive form of the enzyme. No differences existed between the Ca(2+)-induced changes in the intrinsic fluorescence of SR from stimulated and contralateral muscles which fit their similar Ca(2+)-binding characteristics. Taking the proposed architecture of the Ca2(+)-ATPase into consideration, our results suggest that the inactivation relates to a circumscribed structural alteration of the enzyme in sections of the active site consisting of the nucleotide-binding and phosphorylation domains.

scholarly journals Kinetics of Light-Induced Conformational Change in Phot1 LOV2-Jalpha Probed By Transient Tryptophan Fluorescence

2010 ◽  
Vol 98 (3) ◽  
pp. 234a
Author(s):  
Daniel Hoersch ◽  
Farzin Bolourchian ◽  
Harald Otto ◽  
Maarten P. Heyn ◽  
Roberto A. Bogomolni
Keyword(s):  
Conformational Change ◽  
Tryptophan Fluorescence ◽  
Kinetics Of

scholarly journals Positive co-operative binding at two weak lysine-binding sites governs the Glu-plasminogen conformational change

1992 ◽  
Vol 285 (2) ◽  
pp. 419-425 ◽  
Author(s):  
U Christensen ◽  
L Mølgaard
Keyword(s):  
Ligand Binding ◽  
Binding Site ◽  
Conformational Change ◽  
Conformational Changes ◽  
Binding Sites ◽  
High Specificity ◽  
Stopped Flow ◽  
Protein Fluorescence ◽  
Lysine Residues ◽  
Kinetics Of

The kinetics of a series of Glu-plasminogen ligand-binding processes were investigated at pH 7.8 and 25 degrees C (in 0.1 M-NaCl). The ligands include compounds analogous to C-terminal lysine residues and to normal lysine residues. Changes of the Glu-plasminogen protein fluorescence were measured in a stopped-flow instrument as a function of time after rapid mixing of Glu-plasminogen and ligand at various concentrations. Large positive fluorescence changes (approximately 10%) accompany the ligand-induced conformational changes of Glu-plasminogen resulting from binding at weak lysine-binding sites. Detailed studies of the concentration-dependencies of the equilibrium signals and the rate constants of the process induced by various ligands showed the conformational change to involve two sites in a concerted positive co-operative process with three steps: (i) binding of a ligand at a very weak lysine-binding site that preferentially, but not exclusively, binds C-terminal-type lysine ligands, (ii) the rate-determining actual-conformational-change step and (iii) binding of one more lysine ligand at a second weak lysine-binding site that then binds the ligand more tightly. Further, totally independent initial small negative fluorescence changes (approximately 2-4%) corresponding to binding at the strong lysine-binding site of kringle 1 [Sottrup-Jensen, Claeys, Zajdel, Petersen & Magnusson (1978) Prog. Chem. Fibrinolysis Thrombolysis 3, 191-209] were observed for the C-terminal-type ligands. The finding that the conformational change in Glu-plasminogen involves two weak lysine-binding sites indicates that the effect cannot be assigned to any single kringle and that the problem of whether kringle 4 or kringle 5 is responsible for the process resolves itself. Probably kringle 4 and 5 are both participating. The involvement of two lysine binding-sites further makes the high specificity of Glu-plasminogen effectors more conceivable.

scholarly journals Role of the Helical Protrusion in the Conformational Change and Molecular Chaperone Activity of the Archaeal Group II Chaperonin

2004 ◽  
Vol 279 (18) ◽  
pp. 18834-18839 ◽  
Author(s):  
Ryo Iizuka ◽  
Sena So ◽  
Tomonao Inobe ◽  
Takao Yoshida ◽  
Tamotsu Zako ◽  
...  
Keyword(s):  
Conformational Change ◽  
Molecular Chaperone ◽  
Chaperone Activity ◽  
Group Ii ◽  
Group Ii Chaperonin

Kinetics of alkali ion exchange of irradiated glasses

2003 ◽  
Vol 792 ◽  
Author(s):  
Michael I. Ojovan ◽  
William E. Lee
Keyword(s):  
Ion Exchange ◽  
External Irradiation ◽  
Glass Temperature ◽  
Ion Exchange Kinetics ◽  
Radiation Induced ◽  
Exchange Kinetics ◽  
Induced Changes ◽  
Kinetics Of ◽  
Alkali Ion

ABSTRACTThe kinetics of alkali ion exchange of irradiated glasses were investigated using the structural energy barrier model for ion exchange of glasses. Derived rates of alkali ion exchange depend both on irradiation dose D(Gy) and dose rate q(Gy/s) illustrating that some effects cannot be simulated by external irradiation and require in-situ measurements. Higher D and q lead to increased ion exchange rates. Significant changes occur in the activation energies demonstrating a 4 – 6 times decrease depending on glass composition. Radiation-induced changes are higher at relatively low temperatures and are diminished by increased glass temperature. Numerical estimations show that changes in alkali ion exchange kinetics occur at D far below damaging doses.

Protein Kinase C–Induced Changes in the Stoichiometry of ATP Binding Activate Cardiac ATP-Sensitive K+Channels

1996 ◽  
Vol 79 (3) ◽  
pp. 399-406 ◽  
Author(s):  
Peter E. Light ◽  
Aftab A. Sabir ◽  
Bruce G. Allen ◽  
Michael P. Walsh ◽  
Robert J. French
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Atp Binding ◽  
K Channels ◽  
Kinase C ◽  
Induced Changes

scholarly journals In Healthy Young Men, a Short Exhaustive Exercise Alters the Oxidative Stress Only Slightly, Independent of the Actual Fitness

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Maya Finkler ◽  
Ayala Hochman ◽  
Ilya Pinchuk ◽  
Dov Lichtenberg
Keyword(s):  
Physical Fitness ◽  
Serum Lipids ◽  
Ex Vivo ◽  
Young Men ◽  
Exhaustive Exercise ◽  
Progressive Exercise ◽  
Exercise Induced ◽  
Induced Changes ◽  
Kinetics Of ◽  
Apparent Disagreement

The aim of the present study was to evaluate the apparent disagreement regarding the effect of a typical cycling progressive exercise, commonly used to assessVO2max, on the kinetics ofex vivocopper induced peroxidation of serum lipids. Thirty-two (32) healthy young men, aged 24–30 years, who do not smoke and do not take any food supplements, participated in the study. Blood was withdrawn from each participant at three time points (before the exercise and 5 minutes and one hour after exercise). Copper induced peroxidation of sera made of the blood samples was monitored by spectrophotometry. For comparison, we also assayed TBARS concentration and the activity of oxidation-related enzymes. The physical exercise resulted in a slight and reversible increase of TBARS and slight changes in the activities of the studied antioxidant enzymes and the lag preceding peroxidation did not change substantially. Most altered parameters returned to baseline level one hour after exercise. Notably, the exercise-induced changes in OS did not correlate with the physical fitness of the subjects, as evaluated in this study (VO2max= 30–60 mL/min/kg). We conclude that in healthy young fit men a short exhaustive exercise alters only slightly the OS, independent of the actual physical fitness.

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