Bound Form
Bound Form - Related Videos
09:42
Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
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Cited by 6 •
2012
We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.
02:30
Isolation of Small Regulatory RNA–Bound Bacterial Target RNA Using Affinity Purification
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2025
Source: Mercier, N., et. al., MS2-Affinity Purification Coupled with RNA Sequencing in Gram-Positive Bacteria. J. Vis. Exp. (2021)This video demonstrates the isolation of MS2-tagged small regulatory RNA (sRNA) bound to its bacterial target RNA using affinity purification with a maltose-binding protein (MBP)–MS2 coat protein fusion immobilized on amylose resin.
03:47
Screening Inhibitors of Bacterial Membrane-Bound Pyrophosphatase Using a Colorimetric Assay
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2025
Source: Vidilaseris, K., et al. Screening for Thermotoga maritima Membrane-Bound Pyrophosphatase Inhibitors. J. Vis. Exp. (2019)This video demonstrates a colorimetric assay to screen inhibitors of bacterial membrane-bound pyrophosphatase (mPPase) by quantifying orthophosphate release. The method enables identification of compounds that inhibit mPPase from Thermotoga maritima, a potential antimicrobial drug target.
10:42
Flow Cytometric Analysis of Particle-bound Bet v 1 Allergen in PM10
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Cited by 8 •
2016
Here, we present a protocol to quantify allergen-loaded particles by flow cytometry. Ambient particulate matter particles may act as carriers of adsorbed allergens. We show here that flow cytometry, a method widely used to characterize suspended solids >0.5 µm in diameter, can be used to measure these allergen-loaded particles.
12:21
Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram
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Cited by 15 •
2016
This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.
FAQs
Binding is governed by a reversible equilibrium, so molecules can shift between the bound and unbound pools rather than remaining permanently attached. This dynamic balance allows the protein-associated pool to function as a circulating reservoir: as unbound molecules are removed or enter tissues, additional drug can dissociate. The equilibrium therefore helps shape how exposure changes over time.
Unbound molecules are generally the fraction available to cross membranes, reach receptors, undergo metabolism, and be excreted. Consequently, changes in this fraction can alter pharmacological behavior even when the total drug amount appears similar. The bound pool may temporarily limit immediate availability, whereas the unbound pool more directly connects drug concentration with effects and elimination.
Changes in plasma protein concentration can modify how much drug remains associated with binding sites. Competition between drugs for those sites can also shift the equilibrium, increasing or decreasing the unbound fraction. Because the unbound molecules are generally more available for distribution, receptor interaction, metabolism, and excretion, these shifts can contribute to clinically relevant drug interactions.
Researchers can measure or predict the relationship between the bound and unbound pools and then examine how that relationship changes under different conditions. Relevant comparisons include differences in plasma protein concentration and the presence of competing drugs. This approach helps connect binding behavior with expected changes in distribution, duration of action, clearance, and pharmacological response.
Analysis of drug binding helps explain how a compound distributes through the body, how long its effects may persist, and how it is cleared. The equilibrium between pools influences the amount available for membrane passage, receptor interaction, metabolism, and excretion. These relationships also help account for differences in drug behavior among patients.
It is especially useful when interpreting potential drug interactions or differences between patients. A competing drug or altered plasma protein concentration may change the unbound fraction, which can modify the drug’s availability for receptors, metabolism, and excretion. Assessing these shifts provides context for understanding why similar drug exposure conditions may produce different pharmacological outcomes.