Lipid Water Partition Coefficient
Lipid Water Partition Coefficient - Related Videos
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Extraction: Partition and Distribution Coefficients
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2024
The distribution law or Nernst's distribution law is the law that governs the distribution of a solute between two immiscible solvents. This law, also known as the partition law, states that if a solute is added to the mixture of two immiscible solvents at a constant temperature, the solute is distributed between the two solvents in such a way that the ratio of solute concentrations in the solvents remains constant at equilibrium. For extracting a solute from an aqueous phase into an organic...
10:59
Determination of Lipid Raft Partitioning of Fluorescently-tagged Probes in Living Cells by Fluorescence Correlation Spectroscopy (FCS)
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Cited by 10 •
2012
A technique to probe the lipid raft partitioning of fluorescent proteins at the plasma membrane of living cells is described. It takes advantage of the disparity in diffusion times of proteins located inside or outside of lipid rafts. Acquisition can be performed dynamically in control conditions or after drug addition.
14:20
Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example
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Cited by 16 •
2014
Measuring the osmotic water permeability coefficient (Pf) of cells can help understand the regulatory mechanisms of aquaporins (AQPs). Pf determination in spherical plant cell protoplasts presented here involves protoplasts isolation and numerical analysis of their initial rate of volume change as a result of an osmotic challenge during constant bath perfusion.
01:12
Coefficient of Correlation
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2023
The correlation coefficient, r, developed by Karl Pearson in the early 1900s, is numerical and provides a measure of strength and direction of the linear association between the independent variable x and the dependent variable y. If you suspect a linear relationship between x and y, then r can measure how strong the linear relationship is. What the VALUE of r tells us: The value of r is always between –1 and +1: –1 ≤ r ≤ 1. The size of the correlation r indicates the strength of the linear...
01:24
Confidence Coefficient
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2023
The confidence coefficient is also known as the confidence level or degree of confidence. It is the percent expression for the probability, 1-α, that the confidence interval contains the true population parameter assuming that the confidence interval is obtained after sufficient unbiased sampling; for example, if the CL = 90%, then in 90 out of 100 samples the interval estimate will enclose the true population parameter. Here α is the area under the curve, distributed equally under both the...
FAQs
pH changes the balance between ionized and nonionized forms of a compound. Because these forms can distribute differently between lipid and aqueous phases, the measured concentration ratio may change as pH changes. This is especially important for weak acids and bases, since their apparent lipophilicity may depend strongly on the conditions used during measurement.
Ionization can shift a compound’s distribution toward the aqueous phase, whereas the less ionized form may show greater association with the lipid phase. Consequently, the same chemical may behave differently in biological environments with different conditions. Pharmacologists consider this behavior when interpreting likely membrane permeation, gastrointestinal absorption, and tissue distribution.
The partition coefficient describes distribution between lipid and aqueous phases, while solubility describes how much compound can dissolve and protein-binding data indicate association with proteins. These measurements answer different questions and should be interpreted together. A partition value alone cannot fully predict pharmacological behavior when solubility or protein binding substantially affects the compound’s movement and availability.
To determine the value, researchers place the compound in two immiscible phases, allow the system to reach equilibration, and measure the compound’s concentration in each phase. They then calculate the concentration ratio between the lipid and aqueous phases. The selected pH and the compound’s ionization state are important because they can influence the resulting measurement.
The measurement helps compare compounds according to their tendency to enter lipid-rich or aqueous environments. During drug design, it contributes to evaluating possible membrane permeation, gastrointestinal absorption, and tissue distribution. In formulation work, it is considered alongside solubility and protein-binding information to support decisions about how a compound may behave in biological fluids.
A compound’s partitioning tendency provides context for whether it is more likely to remain in aqueous fluids or associate with lipid-rich tissues and membranes. This information can help interpret patterns of absorption and distribution, but it should not be treated as a complete prediction. Solubility, protein binding, pH, and ionization also shape the observed pharmacokinetic behavior.