Urea Adduction
Urea Adduction - Related Videos
07:52
Removal of Branched and Cyclic Compounds by Urea Adduction for Uk'37 Paleothermometry
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2023
Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst As mentioned in previous videos, the product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds. In the case of our two organic paleothermometers (Uk'37 and MBT/CBT), the interest is in only 6 compounds (2 alkenones and 4 isoprenoidal glycerol dialkyl glycerol...
11:46
Single Molecule Analysis of Laser Localized Psoralen Adducts
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2017
Lasers are frequently used in studies of the cellular response to DNA damage. However, they generate lesions whose spacing, frequency, and collisions with replication forks are rarely characterized. Here, we describe an approach that enables the determination of these parameters with laser localized interstrand crosslinks.
08:44
Denaturing Urea Polyacrylamide Gel Electrophoresis (Urea PAGE)
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Cited by 104 •
2009
Denaturing urea polyacrylamide gel electrophoresis is used to separate single-stranded DNA or RNA up to a limit of 500 nucleotides. Urea in combination with heat denatures samples and unstructured single strands migrate within the gel matrix according to their molecular weight.
01:23
Urea Cycle
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2025
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. There are five basic steps in the urea cycle: the conversion of ammonia (NH3) to carbamoyl phosphate the introduction of ornithine in the...
05:34
Denaturing Urea Polyacrylamide Gel Electrophoresis for RNA Analysis: A Technique to Separate Fluorescently Labeled Phosphorylated RNA Oligonucleotides from their Non-Phosphorylated Equivalents
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2025
In this video, we demonstrate a denaturing polyacrylamide gel electrophoresis for the separation of phosphorylated RNA species from their non-phosphorylated counterparts. The RNA species are fluorescently labeled for laser detection on the gel.
FAQs
Molecular shape controls whether a compound can fit within the narrow channels formed by hydrogen-bonded urea molecules. Straight-chain, nonpolar hydrocarbons and fatty acids are compatible with these channels, while branched or cyclic structures are generally excluded. This size-and-shape selectivity allows researchers to distinguish components that may have similar chemical compositions but different molecular architectures.
Urea crystallization converts molecular selectivity into a physical separation. As the urea framework forms, compatible linear molecules become incorporated into crystalline inclusion compounds, producing a selectively precipitated fraction. Researchers can then recover that fraction separately from compounds that do not enter the channels, supporting fractionation of chemically complex samples.
The process provides structural information by separating molecules according to whether their shapes allow channel inclusion. Linear compounds tend to associate with the crystallizing urea structure, whereas branched and cyclic molecules are generally left out. Comparing the resulting fractions can therefore help researchers characterize petroleum-derived mixtures and investigate the composition of organic contaminants.
A conceptual workflow begins with exposing a complex sample to urea while the urea crystallizes. Compatible linear molecules become incorporated into the developing crystalline inclusion compounds, and the precipitated material is then separated for recovery. The resulting fractions can be examined to determine which molecular structures were selectively retained and which were excluded.
Environmental applications described for this approach include petroleum-derived mixtures, lipid-rich samples, and other organic contaminants. These materials often contain compounds with differing chain structures, making selective fractionation useful. By separating structurally distinct components, researchers can improve characterization of mixture composition and support investigations of potential pollutant sources.
Fractionation can reveal differences between straight-chain molecules and compounds with branched or cyclic structures. In environmental science, that information may help assess the composition of petroleum-related materials, distinguish possible pollutant sources, and refine sample-preparation strategies for chemical analysis. The method is therefore useful not only for separation, but also for interpreting molecular structure within complex mixtures.