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#biomolecular interactions

3 public questions tagged with this topic.

Protein-Protein Interaction

Which of the following is distance dependent (

Several biophysical methods probe protein interactions, but only Förster Resonance Energy Transfer exhibits steep distance dependence in 1-10 nanometer range. Efficiency proportional to inverse sixth power of separation imposes strict proximity requirement; beyond approximately 10 nm efficiency becomes negligible. SPR detects refractive index changes at surface, not molecular ruler scale; phage display selects binders; Co-IP isolates complexes regardless of distance. FRET therefore serves as spectroscopic ruler for conformational changes, domain interactions, and complex assembly within macromolecular dimensions near Förster radius.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Hybridization

Which process follows analyte binding in SPR?

After analyte binding reaches steady state in Surface Plasmon Resonance cycle, regeneration step is essential to remove bound analyte while preserving immobilized ligand activity for subsequent cycles. Mild acidic, basic, high salt, or detergent solutions disrupt analyte-ligand interaction without denaturing ligand coating. Successful regeneration restores baseline resonance units, enabling replicate measurements and concentration series on same chip. Immobilization occurs before binding, whereas denaturation or dissolution would destroy sensor functionality. Regeneration conditions require optimization to balance complete removal and ligand stability across multiple analytical cycles.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Hybridization

In SPR, the binding response is measured in:

In Surface Plasmon Resonance instruments, interaction response is quantified as Resonance Units, abbreviated RU, where 1 RU approximately corresponds to binding of 1 picogram per square millimeter on sensor surface. RU reflects shift in resonance angle due to refractive index change proportional to bound mass. Real-time sensograms plot RU versus time, displaying association, equilibrium, and dissociation phases. Units such as nanometers, volts, or generic optical units are not used for SPR quantification. Calibration of RU allows calculation of stoichiometry, kinetics, and affinity constants with high sensitivity and reproducibility.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

View Details