Adding precipitating agent after the cells have been removed has added value because it can:

Question

BlackTom AI · Accepted Answer

Removing cells before adding a precipitating agent preserves the precipitant for interactions with the soluble target, because cell surfaces and debris can adsorb or sequester precipitant molecules non‑specifically. Precipitation in downstream processing relies on controlled addition of agents (e.g., salts, PEG) to drive the target protein out of solution; any reagent consumed by cells or debris reduces the effective dose available for target precipitation and increases process cost and variability.

Relevant concepts:
- Non‑specific binding/adsorption: cell membranes and debris present hydrophobic and charged sites that can bind precipitant or form complexes, removing reagent from solution.
- Precipitant consumption: when precipitant interacts with particulates, more reagent must be added to reach the correct free concentration for target precipitation.
- Process efficiency: minimizing reagent loss and unwanted side reactions improves yield, reduces cost, and simplifies downstream clarification.

Step‑by‑step reasoning:
1. If precipitant is added while cells are present, some will bind to intact cells and cell debris (adsorption, entrapment), reducing free precipitant concentration.
2. Reduced free precipitant can lead to incomplete precipitation of the target, so operators must add extra precipitant to compensate.
3. Removing cells first means the precipitant contacts mostly soluble proteins and impurities, so a smaller, well‑controlled amount achieves the intended precipitation.
4. This improves reagent efficiency, reduces variability, and lowers downstream impurity burdens.

No numerical calculations are required for this conceptual question.

Why the correct option is correct:
The chosen option explicitly states that adding precipitant after cell removal "reduces unintended consumption of precipitant by interactions with cells/cell debris, improving efficiency," which is the primary operational benefit: conserving reagent and ensuring correct effective concentration for target precipitation.

Why the other options are incorrect:
- "Increase precipitant–impurity contact time to improve precipitation": Timing relative to cell removal does not inherently increase contact time with impurities; contact time is controlled by mixing/incubation, not by whether cells are present.
- "Reduce cell–precipitant interactions that could cause lysis and increase impurity levels": While removing cells avoids interactions with cells, the main advantage is conserving precipitant; cell lysis is agent‑dependent and is a secondary concern.
- "Ensure the antibody precipitates rather than remaining soluble": Precipitation outcome depends on concentration, pH and conditions, not simply whether cells were removed first.

Conclusion: Removing cells before adding precipitant primarily reduces unintended precipitant consumption by cells/debris and improves efficiency, matching the provided correct answer.

Adding precipitating agent after the cells have been removed has added value because it can:单项选择题

类似问题

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Adding precipitating agent after the cells have been removed has added value because it can:单项选择题

类似问题

A UF/DF step before Protein A. Which statement is NOT correct?

In an alternative placement described in Chapter 11.4, precipitation is introduced to replace polishing steps, but it has challenges. Which statement is NOT consistent with Chapter 11.4?

According to Chapter 11, precipitation strategy is best described as:

For maximum removal of nonspecifically bound material, the intermediate wash pH should be:

As cell-culture titers increase, which statement is NOT consistent with the passage?

A UF/DF step before Protein A. Which statement is NOT correct?

A UF/DF step before Protein A is most justified when:

You run a gel after a purification experiment. This gel is shown above: The lane that most likely represents your completed purification is lane ____________ This lane would correlate with a ____________ in specific activity.

更多留学生实用工具

希望你的学习变得更简单

You run a gel after a purification experiment. This gel is shown above: The lane that most likely represents your completed purification is lane This lane would correlate with a in specific activity.