Effect of a specific inhibitor on the unfolding and refolding kinetics of dimeric triosephosphate isomerase: Establishing the dimeric and similarly structured nature of the main transition states on the forward and backward reactions

2007 ◽  
Vol 125 (1) ◽  
pp. 172-178 ◽  
Author(s):  
Edith González-Mondragón ◽  
Rafael A. Zubillaga ◽  
Andrés Hernández-Arana
Keyword(s):  
Triosephosphate Isomerase ◽  
Transition States ◽  
Specific Inhibitor ◽  
Main Transition ◽  
Kinetics Of ◽  
Refolding Kinetics

Abnormal Platelet Serotonin Uptake and Binding Sites in Myeloproliferative Disorders

1984 ◽  
Vol 51 (03) ◽  
pp. 349-353 ◽  
Author(s):  
C Caranobe ◽  
P Sié ◽  
F Fernandez ◽  
J Pris ◽  
S Moatti ◽  
...  
Keyword(s):  
Binding Sites ◽  
High Capacity ◽  
Specific Inhibitor ◽  
Myeloproliferative Disorders ◽  
Normal Subjects ◽  
Binding Data ◽  
Full Explanation ◽  
Number Of Binding Sites ◽  
5 Ht Uptake ◽  
Kinetics Of

SummaryA simultaneous investigation of the kinetics of serotonin (5 HT) uptake and of binding sites was carried out in the platelets of normal subjects and of 10 patients affected with various types of myeloproliferative disorders (MD). The 5 HT uptake was analysed according to the Lineweaver-Burk and the Eadie-Hofstee methods. With the two methods, the patient’s platelets exhibited a dramatic reduction of the Vi max and of the Km; in some patients the Eadie-Hofstee analysis revealed that a passive diffusion phenomenon is superimposed on the active 5 HT uptake at least for the higher concentration used. The binding data were analysed with the Scatchard method. Two classes of binding sites (high affinity - low capacity, low affinity - high capacity) were found in normal subjects and patients. Pharmacological studies with imipramine, a specific inhibitor of 5 HT uptake, suggested that both the sites are involved in 5 HT uptake. The number of both binding sites was significantly decreased in patient’s platelets while the affinity constants of these binding sites were not significantly reduced in comparison with those of the control subjects. No correlations were found between Vi max, Km and the number of binding sites. These results suggest that a reduction in the number of platelet membrane acceptors for 5 HT commonly occurs in myeloproliferative disorders but does not provide a full explanation of the uptake defect.

Control of the Reactivation Kinetics of Homodimeric Triosephosphate Isomerase from Unfolded Monomers†

Biochemistry ◽  
2003 ◽  
Vol 42 (11) ◽  
pp. 3311-3318 ◽  
Author(s):  
Viviana Zomosa-Signoret ◽  
Gloria Hernández-Alcántara ◽  
Horacio Reyes-Vivas ◽  
Eduardo Martínez-Martínez ◽  
Georgina Garza-Ramos ◽  
...  
Keyword(s):  
Triosephosphate Isomerase ◽  
Kinetics Of

Nucleoplasmin associates with and is phosphorylated by casein kinase II

1995 ◽  
Vol 108 (2) ◽  
pp. 779-787 ◽  
Author(s):  
I. Vancurova ◽  
T.M. Paine ◽  
W. Lou ◽  
P.L. Paine
Keyword(s):  
Protein Kinase ◽  
Polyclonal Antibody ◽  
Nuclear Transport ◽  
Specific Inhibitor ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Transferase Activity ◽  
Catalytic Subunits ◽  
Kinetics Of

Nucleoplasmin is a phosphorylated nuclear-accumulating protein. We report herein that the kinetics of its cytoplasm-->nucleus transport are affected by its degree of phosphorylation. Therefore, we sought to identify any protein kinase which specifically associates with nucleoplasmin. We discovered that nucleoplasmin co-isolates by two independent methods (immunoabsorption and chromatography) in a complex including a kinase which phosphorylates nucleoplasmin. The co-purifying kinase is casein kinase II-like because: (i) it phosphorylates casein; (ii) its phospho-transferase activity can be competed out by GTP; (iii) it is stimulated by polylysine; and (iv) it is inhibited by heparin. Moreover, a polyclonal antibody to the alpha (38 kDa) and alpha' (36 kDa) catalytic subunits of casein kinase II specifically recognizes 38 and 36 kDa polypeptides in the nucleoplasmin-complex, and a specific inhibitor of casein kinase II inhibits nucleoplasmin's nuclear transport. Additionally, we found that phosphorylation of nucleoplasmin by its associated casein kinase II is strongly inhibited by histones and that, in addition to nucleoplasmin, another protein (p100) in the nucleoplasmin-complex is phosphorylated by casein kinase II.

scholarly journals Oxidative folding of hirudin in human serum

2006 ◽  
Vol 394 (1) ◽  
pp. 249-257 ◽  
Author(s):  
Jui-Yoa Chang ◽  
Bao-Yun Lu ◽  
Por-Hsiung Lai
Keyword(s):  
Amino Acids ◽  
Protein Folding ◽  
Human Serum ◽  
Initial Phase ◽  
Macromolecular Crowding ◽  
Specific Inhibitor ◽  
Crowding Effect ◽  
Oxidative Folding ◽  
Disulphide Bonds ◽  
Kinetics Of

Human serum contains factors that promote oxidative folding of disulphide proteins. We demonstrate this here using hirudin as a model. Hirudin is a leech-derived thrombin-specific inhibitor containing 65 amino acids and three disulphide bonds. Oxidative folding of hirudin in human serum is shown to involve an initial phase of rapid disulphide formation (oxidation) to form the scrambled isomers as intermediates. This is followed by the stage of slow disulphide shuffling of scrambled isomers to attain the native hirudin. The kinetics of regenerating the native hirudin depend on the concentrations of both hirudin and human serum. Quantitative regeneration of native hirudin in undiluted human serum can be completed within 48 h, without any redox supplement. These results cannot be adequately explained by the existing oxidized thiol agents in human serum or the macromolecular crowding effect, and therefore indicate that human serum may contain yet to be identified potent oxidase(s) for assisting protein folding.

Imatinib Mesylate (STI571) Abrogates the Resistance to Doxorubicin in K562 Chronic Myeloid Leukemia Cells by Inhibition of BCR/ABL Kinase-Mediated DNA Repair.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1525-1525
Author(s):  
Ireneusz Majsterek ◽  
Janusz Blasiak ◽  
Artur Slupianek ◽  
Tomasz Skorski
Keyword(s):  
Drug Resistance ◽  
Dna Repair ◽  
Imatinib Mesylate ◽  
Lymphoblastic Leukemia ◽  
Specific Inhibitor ◽  
K562 Cells ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Abl Kinase ◽  
Kinetics Of

Abstract Imatinib mesylate (STI571), a specific inhibitor of the BCR/ABL tyrosine kinase, exhibits potent antileukemic effects in the treatment of chronic myelogenous leukemia (CML). However, the precise mechanisms by which inhibition of BCR/ABL activity results in pharmacological responses remain unknown. BCR/ABL-positive human CML cells resistant to doxorubicin K562doxoR and their sensitive K562doxoS counterparts were used to determine the mechanism by which the STI571 inhibitor may overcome drug resistance. K562 wild type cells and CCRF-CEM lymphoblastic leukemia cells without BCR/ABL were used as controls. We examined kinetics of DNA repair after cell treatment with the drug by the alkaline comet assay. MTT assay was used to estimate resistance against doxorubicin and Western Blot analysis with Crk-L antibody was performed to evaluate BCR/ABL kinase inhibition by STI571. We provide evidence that treatment of CML-derived BCR/ABL-expressing leukemia K562 cells with STI571 results in the inhibition of DNA repair and abrogation of the resistance of these cells to doxorubicin. We found that doxorubicin-resistant K562doxoR cells exhibited accelerated kinetics of DNA repair in comparison to doxorubicin-sensitive K562doxoS cells. Inhibition of BCR/ABL kinase in K562doxoR cells with 1 μM STI571 decreased the kinetics of DNA repair and abrogated drug resistance. The results suggest that STI571-mediated inhibition of BCR/ABL kinase activity can affect the effectiveness of the DNA repair pathways, which in turn may enhance drug sensitivity of leukemia cells.

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