Evidence from activation parameters for enzyme active centre desolvation promoted by specific binding interactions

1994 ◽  
Vol 22 (2) ◽  
pp. 213S-213S
Author(s):  
GEOFFREY W. MELLOR ◽  
MARK P. THOMAS ◽  
SHERAZ GUL ◽  
MICHAEL A. NOBLE ◽  
EMRYS W. THOMAS ◽  
...  
Keyword(s):  
Specific Binding ◽  
Activation Parameters ◽  
Active Centre ◽  
Binding Interactions

scholarly journals The interplay of electrostatic and binding interactions determining active centre chemistry and catalytic activity in actinidin and papain

1989 ◽  
Vol 257 (1) ◽  
pp. 309-310 ◽  
Author(s):  
K Brocklehurst ◽  
M O'Driscoll ◽  
D Kowlessur ◽  
I R Phillips ◽  
W Templeton ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Centre ◽  
Binding Interactions

scholarly journals Interaction of Bacillus thuringiensis Cry1 and Vip3A Proteins with Spodoptera frugiperda Midgut Binding Sites

2009 ◽  
Vol 75 (7) ◽  
pp. 2236-2237 ◽  
Author(s):  
Janete A. D. Sena ◽  
Carmen Sara Hernández-Rodríguez ◽  
Juan Ferré
Keyword(s):  
Bacillus Thuringiensis ◽  
Spodoptera Frugiperda ◽  
Binding Sites ◽  
Specific Binding ◽  
Binding Assays ◽  
Binding Interactions ◽  
Specific Binding Sites

ABSTRACT Vip3Aa, Vip3Af, Cry1Ab, and Cry1Fa were tested for their toxicities and binding interactions. Vip3A proteins were more toxic than Cry1 proteins. Binding assays showed independent specific binding sites for Cry1 and Vip3A proteins. Cry1Ab and Cry1Fa competed for the same binding sites, whereas Vip3Aa competed for those of Vip3Af.

scholarly journals Role of Capsular Colanic Acid in Adhesion of Uropathogenic Escherichia coli

2003 ◽  
Vol 69 (8) ◽  
pp. 4474-4481 ◽  
Author(s):  
Andrea Hanna ◽  
Michael Berg ◽  
Valerie Stout ◽  
Anneta Razatos
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Bacterial Adhesion ◽  
Specific Binding ◽  
Binding Interactions ◽  
Colanic Acid ◽  
Mutant Strains ◽  
Tract Infections ◽  
Repulsive Forces

ABSTRACT Urinary tract infections are the most common urologic disease in the United States and one of the most common bacterial infections of any organ system. Biofilms persist in the urinary tract and on catheter surfaces because biofilm microorganisms are resistant to host defense mechanisms and antibiotic therapy. The first step in the establishment of biofilm infections is bacterial adhesion; preventing bacterial adhesion represents a promising method of controlling biofilms. Evidence suggests that capsular polysaccharides play a role in adhesion and pathogenicity. This study focuses on the role of physiochemical and specific binding interactions during adhesion of colanic acid exopolysaccharide mutant strains. Bacterial adhesion was evaluated for isogenic uropathogenic Escherichia coli strains that differed in colanic acid expression. The atomic force microscope (AFM) was used to directly measure the reversible physiochemical and specific binding interactions between bacterial strains and various substrates as bacteria initially approach the interface. AFM results indicate that electrostatic interactions were not solely responsible for the repulsive forces between the colanic acid mutant strains and hydrophilic substrates. Moreover, hydrophobic interactions were not found to play a significant role in adhesion of the colanic acid mutant strains. Adhesion was also evaluated by parallel-plate flow cell studies in comparison to AFM force measurements to demonstrate that prolonged incubation times alter bacterial adhesion. Results from this study demonstrate that the capsular polysaccharide colanic acid does not enhance bacterial adhesion but rather blocks the establishment of specific binding as well as time-dependent interactions between uropathogenic E. coli and inert substrates.

scholarly journals Chaotropic and Kosmotropic Anions Regulate the Outcome of Enzyme-Mediated Dynamic Combinatorial Libraries of Cyclodextrins in Two Different Ways

2021 ◽  
Vol 9 ◽  
Author(s):  
Andreas Erichsen ◽  
Dennis Larsen ◽  
Sophie R. Beeren
Keyword(s):  
Specific Binding ◽  
Combinatorial Libraries ◽  
Hofmeister Series ◽  
Cyclodextrin Glucanotransferase ◽  
Binding Interactions ◽  
Guest Molecules ◽  
High Concentrations ◽  
Chaotropic Anions

We demonstrate how different anions from across the Hofmeister series can influence the behavior of enzyme-mediated dynamic combinatorial libraries of cyclodextrins (CDs). Using cyclodextrin glucanotransferase to catalyze reversible transglycosylation, dynamic mixtures of interconverting cyclodextrins can be formed wherein the relative concentrations of α-CD, β-CD and γ-CD is determined by their intrinsic stabilities and any stabilizing influences of added template (guest) molecules. Here, we find that addition of high concentrations of kosmotropic anions can be used to enhance the effects of added hydrophobic templates, while chaotropic anions can themselves act as templates, causing predictable and significant changes in the cyclodextrin composition due to weak, but specific, binding interactions with α-CD.

Inhibitor Binding Assay of rat Serum Angiotensin Converting Enzyme

1984 ◽  
Vol 67 (2) ◽  
pp. 237-241 ◽  
Author(s):  
Ilkka Tikkanen ◽  
Frej Fyhrquist ◽  
Terje Forslund
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Enzyme Assay ◽  
Binding Assay ◽  
Specific Binding ◽  
Great Sensitivity ◽  
Converting Enzyme ◽  
Inhibitor Binding ◽  
Rat Serum ◽  
Active Centre ◽  
Serum Angiotensin Converting Enzyme

1. Based on a specific binding of labelled inhibitor to the enzyme active centre, a new principle of enzyme assay, inhibitor binding assay (IBA), was developed and applied to measurement of rat serum angiotensin converting enzyme (ACE). 2. Serum diluted 1:50 was incubated with 125I-labelled ACE inhibitor, 351A, at pH 7.0, 37°C, for 2 h. Inhibitor bound to ACE was separated with coated charcoal and results were calculated from a standard curve. 3. The advantages offered by the novel inhibitor binding assay include simplicity, specificity, absence of interference by other enzymes or immunological cross-reactions, and great sensitivity enabling measurement of ACE in concentrations less than 0.1 units/ml. 4. This principle of enzyme assay will not only have potential new applications for research involving ACE but may also be extended to other enzymes.

scholarly journals Thermodynamic and kinetic studies on saccharide binding to soya-bean agglutinin

1986 ◽  
Vol 234 (3) ◽  
pp. 515-522 ◽  
Author(s):  
M J Swamy ◽  
M V Krishna Sastry ◽  
M I Khan ◽  
A Surolia
Keyword(s):  
Thermodynamic Parameters ◽  
Specific Binding ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Blue Shift ◽  
Single Step ◽  
Soya Bean ◽  
Saccharide Binding ◽  
Delta G ◽  
Kinetics Of

The fluorescence of N-dansylgalactosamine [N-(5-dimethylaminonaphthalene-1-sulphonyl)galactosamine] was enhanced 11-fold with a 25 nm blue-shift in the emission maximum upon binding to soya-bean agglutinin (SBA). This change was used to determine the association constants and thermodynamic parameters for this interaction. The association constant of 1.51 × 10(6) M-1 at 20 degrees C indicated a very strong binding, which is mainly due to a relatively small entropy value, as revealed by the thermodynamic parameters: delta G = −34.7 kJ × mol-1, delta H = −37.9 kJ × mol-1 and delta S = −10.9 J × mol-1 × K-1. The specific binding of this sugar to SBA shows that the lectin can accommodate a large hydrophobic substituent on the C-2 of galactose. Binding of non-fluorescent ligands, studied by monitoring the fluorescence changes when they are added to a mixture of SBA and N-dansylgalactosamine, indicates that a hydrophobic substituent at the anomeric position increases the affinity of the interaction. The C-6 hydroxy group also stabilizes the binding considerably. Kinetics of binding of N-dansylgalactosamine to SBA studied by stopped-flow spectrofluorimetry are consistent with a single-step mechanism and yielded k+1 = 2.4 × 10(5) M-1 × s-1 and k-1 = 0.2 s-1 at 20 degrees C. The activation parameters indicate an enthalpicly controlled association process.

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