affinity

Examples of affinity in the following topics:

• Antibody Genes and Diversity

  • This serves to increase the diversity of the antibody pool and impacts the antibody's antigen-binding affinity.
  • Some point mutations will result in the production of antibodies that have a lower affinity with their antigen than the original antibody, and some mutations will generate antibodies with a higher affinity.
  • B cells that express higher affinity antibodies on their surface will receive a strong survival signal during interactions with other cells, whereas those with lower affinity antibodies will not, and will die by apoptosis.
  • Thus, B cells expressing antibodies with a higher affinity for the antigen will outcompete those with weaker affinities for function and survival.
  • The process of generating antibodies with increased binding affinities is called affinity maturation.

• Mapping Protein-Protein Interactions

  • The most widely employed tools are the yeast two-hybrid system and affinity purification coupled to mass spectrometry.
  • Affinity purification of protein complexes coupled to mass spectrometry is carried out as follows: a specific protein (the bait) is manipulated to express an affinity tag.
  • The tag serves as a tool to purify the bait protein and associated proteins by affinity chromatography.

• Iron-Binding Proteins

  • Transferrin has a molecular weight of around 80 KDa and contains two specific high-affinity Fe(III) binding sites.
  • The affinity of transferrin for Fe(III) is extremely high (1023 M−1 at pH 7.4), but decreases progressively with decreasing pH below neutrality.

• Purifying Proteins by Affinity Tag

  • Affinity tags are appended to proteins so that they can be purified from their crude biological source using an affinity technique.
  • Some affinity tags have a dual role as a solubilization agent, such as MBP and GST.
  • Epitope tags are short peptide sequences which are chosen because high-affinity antibodies can be reliably produced in many different species.

• Siderophores

  • This specific type of siderophore is the strongest identified siderophore, to date, with an extremely high binding affinity to Fe3+.
  • Due to the high-binding affinity of enterobactin, the bacteria require a highly specific enzyme, ferrienterobactin esterase, to cleave the iron from the complex.

• Fluorescent Antibodies

  • These compounds have high affinity for proteins with which they conjugate.

• DNA Protection Analysis

  • By varying the concentration of the DNA-binding protein, the binding affinity of the protein can be estimated according to the minimum concentration of protein at which a footprint is observed.

• Crystallographic Analysis

  • .), purification of recombinant proteins (such as chromatography of affinity and gel filtration), enzymatic tests and inhibition measurement (spectrophotometry), crystallization, x-rays crystallography and structural analysis, interactions determination (microcalorimetry, fluorescence, BIAcore), conformational analyses (circular dichroism, ultracentrifugation, light scattering), modifications analysis (mass spectrometry), bioinformatics, and molecular modelisation.

• Clonal Selection of Antibody-Producing Cells

  • The increase is accompanied by affinity maturation which induces the survival of B cells that bind to the particular antigen with high affinity.

• Sodium Pumps as an Alternative to Proton Pumps

  • The phosphorylated form of the pump has a low affinity for Na+ ions, so they are released.The pump binds 2 extracellular K+ ions.
  • This causes the dephosphorylation of the pump, reverting it to its previous conformational state, transporting the K+ ions into the cell.The unphosphorylated form of the pump has a higher affinity for Na+ ions than K+ ions, so the two bound K+ ions are released.