scholarly journals Correlation between composition and activity of gold nanoparticle conjugates with streptococcal protein G

2020 ◽  
Vol 10 (2) ◽  
pp. 4988-4992
Keyword(s):  
Dissociation Constant ◽  
Equilibrium Constants ◽  
Gold Surface ◽  
Binding Activity ◽  
Protein G ◽  
Binding Ability ◽  
Adsorbed Protein ◽  
Streptococcal Protein G ◽  
The Stability ◽  
Nanoparticle Complex

The composition of the conjugates of gold nanoparticles with streptococcal protein G was studied using fluorescence spectroscopy. The method for determining the composition is based on measuring the intrinsic fluorescence of tryptophan as part of the protein. The equilibrium constants of protein binding by the gold surface were determined using the Sketchard method. An increase in the dissociation constant of the protein–nanoparticle complex for increasing the amount of bound protein was demonstrated, and a relationship was established between the stability of the conjugates, their antigen-binding activity, and the dissociation constant. The effectiveness of the conjugates of different compositions in immunochromatographic assay of specific antibodies against the lipopolysaccharide antigen of Brucella abortus was compared. The binding ability of the conjugates increased along with the amount of protein G to ~200 molecules per nanoparticle. A further increase in the amount of adsorbed protein led to a deterioration in the functional activity of the conjugates.

Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

1985 ◽  
Vol 50 (3) ◽  
pp. 581-599 ◽  
Author(s):  
Petr Vaňura ◽  
Emanuel Makrlík
Keyword(s):  
Stability Constants ◽  
Organic Phase ◽  
Equilibrium Constants ◽  
Minor Role ◽  
Nitrobenzene Solution ◽  
Ligand Structure ◽  
Stability Constants Of Complexes ◽  
Separation Factors ◽  
The Stability ◽  
A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

The serum albumin-binding region of streptococcal protein G: a bacterial fusion partner with carrier-related properties

1997 ◽  
Vol 201 (1) ◽  
pp. 115-123 ◽  
Author(s):  
Anders Sjölander ◽  
Per-Åke Nygren ◽  
Stefan Ståhl ◽  
Klavs Berzins ◽  
Mathias Uhlén ◽  
...  
Keyword(s):  
Serum Albumin ◽  
Protein G ◽  
Albumin Binding ◽  
Fusion Partner ◽  
Binding Region ◽  
Streptococcal Protein G

The Third IgG-Binding Domain from Streptococcal Protein G

1994 ◽  
Vol 243 (5) ◽  
pp. 906-918 ◽  
Author(s):  
Jeremy P. Derrick ◽  
Dale B. Wigley
Keyword(s):  
Binding Domain ◽  
Protein G ◽  
The Third ◽  
Igg Binding ◽  
Streptococcal Protein G

scholarly journals Mechanism for Increase in Intracellular Concentration of Free Calcium in Fertilized Sea Urchin Egg

1974 ◽  
Vol 63 (3) ◽  
pp. 374-388 ◽  
Author(s):  
Masahisa Nakamura ◽  
Ikuo Yasumasu
Keyword(s):  
Dissociation Constant ◽  
Sea Urchin ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Intracellular Concentration ◽  
Sodium Ion ◽  
Free Calcium ◽  
Binding Ability ◽  
Sea Urchin Egg ◽  
Fertilized Egg

Intracellular free calcium concentration in the sea urchin egg was calculated to increase from 0.1 mM in an unfertilized egg to 1 mM in a fertilized egg 10 min after fertilization, based on measurement of the dissociation constant between free calcium and sea urchin egg homogenate. The dissociation constant between free calcium (dialyzable calcium) and homogenate of sea urchin eggs was measured by means of dialysis equilibrium. The dissociation constant of the unfertilized egg was about 10–4 M and that of the fertilized egg was about 10–3 M in three species of sea urchin, Hemicentrotus pulcherrimus, Anthocidaris crassispina, and Pseudocentrotus depressus. An increase in the dissociation constant of the unfertilized egg homogenate was observed after the addition of calcium ion at a concentration above 0.3 mM, the dissociation constant becoming the same as that observed in the fertilized egg homogenate after the administration of CaCl2 at a concentration above 1 mM. Sodium ion also caused a decrease in the calcium-binding ability of the unfertilized egg homogenate. Therefore, penetration of calcium ion or sodium ion upon fertilization might induce an increase in the dissociation constant and then intracellular concentration of free calcium would increase at fertilization. Almost all calcium-binding ability of the egg homogenate was found in the microsomal fraction, and the substance which bound calcium was thought to be protein in nature, since trypsin could decrease the level of calcium-binding substance in the homogenate of the eggs.

scholarly journals Mutational and biophysical robustness in a pre-stabilized monobody

2020 ◽  
Author(s):  
Peter G. Chandler ◽  
Li Lynn Tan ◽  
Benjamin T. Porebski ◽  
James S. Green ◽  
Blake T. Riley ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Therapeutic Potential ◽  
Binding Activity ◽  
Protein Domain ◽  
Long Term Stability ◽  
Accelerated Stability ◽  
Fibronectin Type Iii ◽  
The Stability ◽  
Complex Architecture ◽  
Shelf Stable

AbstractThe fibronectin type III (FN3) monobody domain is a promising non-antibody scaffold which features a less complex architecture than an antibody while maintaining analogous binding loops. We previously developed FN3Con, a hyper-stable monobody derivative with diagnostic and therapeutic potential. Pre-stabilization of the scaffold mitigates the stability-function trade-off commonly associated with evolving a protein domain towards biological activity. Here, we aimed to examine if the FN3Con monobody could take on antibody-like binding to therapeutic targets, while retaining its extreme stability. We targeted the first of the Adnectin derivative of monobodies to reach clinical trials, which was engineered by directed evolution for binding to the therapeutic target VEGFR2; however, this function was gained at the expense of large losses in thermostability and increased oligomerisation. In order to mitigate these losses, we grafted the binding loops from Adnectin-anti-VEGFR2 (CT-322) onto the pre-stabilized FN3Con scaffold to produce a domain that successfully bound with high affinity to the therapeutic target VEGFR2. This FN3Con-anti-VEGFR2 construct also maintains high thermostability, including remarkable long-term stability, retaining binding activity after 2 years of storage at 36 °C. Further investigations into buffer excipients doubled the presence of monomeric monobody in accelerated stability trials. These data suggest that loop grafting onto a pre-stabilized scaffold is a viable strategy for the development of monobody domains with desirable biophysical characteristics, and is therefore well-suited to applications such as the evolution of multiple paratopes or shelf-stable diagnostics and therapeutics.

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