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Related Concept Videos

Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin01:26

Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin

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Directly acting muscle relaxants like dantrolene and botulinum toxin (BoNT) have distinct mechanisms and applications. Dantrolene, a hydantoin derivative, acts on the ryanodine receptor (RYR1) in skeletal muscle cells. RYR1 are calcium channels present at the sarcoplasmic reticulum membrane. In response to excitation, they release calcium ions from the sarcoplasmic reticulum to the cytosol. Calcium promotes actin-myosin-mediated contraction of muscles.
The binding of dantrolene to the RYR1...
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Buffers02:56

Buffers

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A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a buffer. Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl...
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Buffers: Buffer Capacity01:09

Buffers: Buffer Capacity

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Buffer capacity is the quantitative measure of a buffer to resist the change in pH. As shown in the following equation, the buffer capacity, denoted by 'beta', is expressed as the number of moles of acid or base needed to change the pH of a one-liter buffer solution by 1 unit. Here, Ca and Cb indicate the number of moles of acid and base, respectively. Note that dpH represents the change in pH.
In the graph, pH is plotted as a function of the number of moles of base (Cb) added to a weak...
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Buffer Effectiveness02:19

Buffer Effectiveness

55.1K
Buffer solutions do not have an unlimited capacity to keep the pH relatively constant . Instead, the ability of a buffer solution to resist changes in pH relies on the presence of appreciable amounts of its conjugate weak acid-base pair. When enough strong acid or base is added to substantially lower the concentration of either member of the buffer pair, the buffering action within the solution is compromised.
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Urea Cycle01:23

Urea Cycle

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The urea cycle describes how liver cells convert ammonia to urea. Ammonia is a toxic waste product of protein catabolism. Land animals must convert ammonia into the less toxic urea which can be safely eliminated by the kidneys through urine. Marine animals excrete ammonia directly, and the surrounding water dilutes the ammonia to safe levels.
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Calculating pH Changes in a Buffer Solution02:45

Calculating pH Changes in a Buffer Solution

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A buffer can prevent a sudden drop or increase in the pH of a solution after the addition of a strong acid or base up to its buffering capacity; however, such addition of a strong acid or base does result in the slight pH change of the solution. The small pH change can be calculated by determining the resulting change in the concentration of buffer components, i.e., a weak acid and its conjugate base or vice versa. The concentrations obtained using these stoichiometric calculations can be used...
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Related Experiment Video

Updated: Jan 27, 2026

Ultrasound-guided Botulinum Toxin-A Injections: A Method of Treating Sialorrhea
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Extraction of Botulinum Toxin with Urea-Buffer.

Yinchun Wang1, Hiroshi Sugiyama1

  • 1Food Research Institute and Department of Bacteriology, University of Wisconsin, Madison, Wisconsin 53706.

Journal of Food Protection
|March 30, 2019
PubMed
Summary

Urea-containing buffer extracts more botulinum toxin from wieners and soybean foods than standard buffer. This improved extraction method enhances toxin detection in food safety studies.

Area of Science:

  • Food Microbiology
  • Analytical Chemistry

Background:

  • Clostridium botulinum spores can contaminate food products, leading to toxin production.
  • Accurate detection of botulinum toxin is crucial for food safety.

Purpose of the Study:

  • To evaluate the efficacy of urea-buffer extraction for detecting botulinum toxin in wieners and soybean foods.
  • To compare toxin yield from urea-buffer versus standard buffer extraction.

Main Methods:

  • Food samples (wieners, tofu, tempeh) inoculated with Clostridium botulinum spores.
  • Extraction of samples using buffers with and without 2 M urea.
  • Quantification of botulinum toxin using LD50 assays.

Main Results:

  • Botulinum toxin was detected in more samples extracted with urea-buffer.

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  • Urea-buffer extracted 30-100% more toxin from wieners compared to standard buffer.
  • Enhanced toxin recovery observed in soybean food matrices.

    • Conclusions:

    • Incorporating 2 M urea into extraction buffers significantly improves botulinum toxin recovery from wieners and soybean foods.
    • Urea-buffer extraction is a more sensitive method for detecting botulinum toxin in these food types.
    • This method can enhance the reliability of food safety testing for botulism-causing agents.