Studies on the interaction of glutamate dehydrogenase with aporheine

1984 ◽  
Vol 49 (9) ◽  
pp. 2001-2011
Author(s):  
Jan Kovář ◽  
Luděk Matyska
Keyword(s):  
Binding Site ◽  
Glutamate Dehydrogenase ◽  
Inhibitory Action ◽  
Positive Charge ◽  
Alkaline Media ◽  
Acidic Ph ◽  
High Affinity ◽  
Good Substrate ◽  
Kinetics Of

The effect was examined of two inhibitors, aporheine and thyroxine, on the kinetics of action of glutamate dehydrogenase in the presence of the coenzyme, NADH, in an inhibiting excess. from the results obtained it appears probable that these two competing ligands do not bind to the regulatory binding site of the enzyme. If the good substrate, glutamate, is replaced by a poor one, such as alanine, aporheine can behave under certain conditions as an activator; this phenomenon is most likely due to fact, like in other cases, that the association of alanine wit the enzyme-coenzyme complex is the slowest step of the reaction. The inhibitory action of aporheine in alkaline media is more complicated than its action at neutral and acidic pH. The sigmoid dependence of inhibition on aporheine concentration is best interpreted as a result of the induction of the second binding site of the enzyme subunit for aporheine after the binding of the first molecule of this ligand. The results obtained indicate the presence of a positive charge localized in the neighborhood of the binding site for the first aporheine molecule and also the important role played by some group of the enzyme with a pK-value about 8 during the induction of the second binding site with a relative high affinity for this ligand.

Inhibition of aldehyde reductase I by some isoquinoline alkaloids

1987 ◽  
Vol 52 (9) ◽  
pp. 2338-2346 ◽  
Author(s):  
Hana Paulová ◽  
Jan Kovář ◽  
Jiří Plocek ◽  
Jiří Slavík
Keyword(s):  
Alcohol Dehydrogenase ◽  
Binding Site ◽  
Inhibitory Action ◽  
Positive Charge ◽  
Aldehyde Reductase ◽  
Isoquinoline Alkaloids ◽  
Active Centre ◽  
Hydrophobic Nature ◽  
Kinetics Of

Aldehyde reductase I has been found to be inhibited by certain isoquinoline alkaloids (protoberberines, protopines, benzylisoquinolines, benzyltetrahydroisoquinolines, phthalideisoquinolines, pavinanes) and narceine imide. The sensitivity of this enzyme to the compounds tested was compared with that of alcohol dehydrogenase and/or aldehyde reductase II to them; alcohol dehydrogenase proved more selective in binding the alkaloids. The kinetics of the inhibitory action of berberine and other results suggest that the binding site of aldehyde reductase I for alkaloids is relatively large, has a hydrophobic nature, and probably contains a group with a positive charge. This binding site is probably not identical with the active centre of the nezyme.

scholarly journals Kinetics of the multitasking high-affinity Win binding site of WDR5 in restricted and unrestricted conditions

2021 ◽  
Author(s):  
Ali Imran ◽  
Brandon S. Moyer ◽  
Ashley J. Canning ◽  
Dan Kalina ◽  
Thomas M Duncan ◽  
...  
Keyword(s):  
Binding Site ◽  
Primary Role ◽  
Dissociation Kinetics ◽  
High Affinity ◽  
Histone 3 ◽  
Quantitative Understanding ◽  
Slow Dissociation ◽  
Kinetics Of ◽  
Association Kinetics

Recent advances in quantitative proteomics show that WD40 proteins play a pivotal role in numerous cellular networks. Yet, they have been fairly unexplored and their physical associations with other proteins are ambiguous. A quantitative understanding of these interactions has wide-ranging significance. WD40 repeat protein 5 (WDR5) interacts with all members of human SET1/MLL methyltransferases, which regulate methylation of the histone 3 lysine 4 (H3K4). Here, using real-time binding measurements in a high-throughput setting, we identified the kinetic fingerprint of  transient associations between WDR5 and 14-residue WDR5 interaction (Win) motif peptides of each SET1 protein (SET1Win). Our results reveal that the high-affinity WDR5-SET1Win interactions feature slow association kinetics. This finding is likely due to the requirement of SET1Win to insert into the narrow WDR5 cavity, also named the Win binding site. Furthermore, our explorations indicate fairly slow dissociation kinetics. This conclusion is in accordance with the primary role of WDR5 in maintaining the functional integrity of a large multisubunit complex, which regulates the histone methylation. Because the Win binding site is considered a key therapeutic target, the immediate outcomes of this study could form the basis for accelerated developments in medical biotechnology.

scholarly journals Heterocyclic boronic acids display sialic acid selective binding in a hypoxic tumor relevant acidic environment

2017 ◽  
Vol 8 (9) ◽  
pp. 6165-6170 ◽  
Author(s):  
A. Matsumoto ◽  
A. J. Stephenson-Brown ◽  
T. Khan ◽  
T. Miyazawa ◽  
H. Cabral ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Boronic Acids ◽  
Sialic Acids ◽  
Strong Interactions ◽  
Acidic Ph ◽  
Acidic Environment ◽  
Selective Binding ◽  
High Affinity ◽  
Ph Conditions ◽  
Hypoxic Tumor

A group of heterocyclic boronic acids demonstrating unusually high affinity and selectivity for sialic acids are described, with strong interactions under the weakly acidic pH conditions associated with a hypoxic tumoral microenvironment.

scholarly journals Functional characterization of the dimerization domain of the ferric uptake regulator (Fur) of Pseudomonas aeruginosa

2006 ◽  
Vol 400 (3) ◽  
pp. 385-392 ◽  
Author(s):  
Erdeni Bai ◽  
Federico I. Rosell ◽  
Bao Lige ◽  
Marcia R. Mauk ◽  
Barbara Lelj-Garolla ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Metal Ions ◽  
Binding Site ◽  
Metal Ion ◽  
Association Constants ◽  
Ion Binding ◽  
Ferric Uptake Regulator ◽  
Metal Ion Binding ◽  
Dimerization Domain ◽  
High Affinity

The functional properties of the recombinant C-terminal dimerization domain of the Pseudomonas aeruginosa Fur (ferric uptake regulator) protein expressed in and purified from Escherichia coli have been evaluated. Sedimentation velocity measurements demonstrate that this domain is dimeric, and the UV CD spectrum is consistent with a secondary structure similar to that observed for the corresponding region of the crystallographically characterized wild-type protein. The thermal stability of the domain as determined by CD spectroscopy decreases significantly as pH is increased and increases significantly as metal ions are added. Potentiometric titrations (pH 6.5) establish that the domain possesses a high-affinity and a low-affinity binding site for metal ions. The high-affinity (sensory) binding site demonstrates association constants (KA) of 10(±7)×106, 5.7(±3)×106, 2.0(±2)×106 and 2.0(±3)×104 M−1 for Ni2+, Zn2+, Co2+ and Mn2+ respectively, while the low-affinity (structural) site exhibits association constants of 1.3(±2)×106, 3.2(±2)×104, 1.76(±1)×105 and 1.5(±2)×103 M−1 respectively for the same metal ions (pH 6.5, 300 mM NaCl, 25 °C). The stability of metal ion binding to the sensory site follows the Irving–Williams order, while metal ion binding to the partial sensory site present in the domain does not. Fluorescence experiments indicate that the quenching resulting from binding of Co2+ is reversed by subsequent titration with Zn2+. We conclude that the domain is a reasonable model for many properties of the full-length protein and is amenable to some analyses that the limited solubility of the full-length protein prevents.

Characterization of a Specific, High Affinity [3H]Arginine8Vasopressin-Binding Site on Liver Microsomes from Different Strains of Rat and the Role of Magnesium*

Endocrinology ◽  
1986 ◽  
Vol 118 (3) ◽  
pp. 990-998 ◽  
Author(s):  
VENKAT GOPALAKRISHNAN ◽  
CHRIS R. TRIGGLE ◽  
PRAKASH V. SULAKHE ◽  
J. ROBERT McNEILL
Keyword(s):  
Binding Site ◽  
Liver Microsomes ◽  
High Affinity ◽  
Different Strains

Iron-Blocking the High-Affinity Mn-Binding Site in Photosystem II Facilitates Identification of the Type of Hydrogen Bond Participating in Proton-Coupled Electron Transport via YZ•†

Biochemistry ◽  
2005 ◽  
Vol 44 (28) ◽  
pp. 9746-9757 ◽  
Author(s):  
Boris K. Semin ◽  
Elena R. Lovyagina ◽  
Kirill N. Timofeev ◽  
Ilya I. Ivanov ◽  
Andrei B. Rubin ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Binding Site ◽  
High Affinity
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