Methyl Loss
Methyl Loss - Related Videos
08:47
DNA Methylation Analysis
0 Views •
2023
Methylation at CpG dinucleotides is a chemical modification of DNA hypothesized to play important roles in regulating gene expression. In particular, the methylation of clusters of methylation sites, called “CpG islands”, near promoters and other gene regulatory elements may contribute to the stable silencing of genes, for example, during epigenetic processes such as genomic imprinting and X-chromosome inactivation. At the same time, aberrant CpG methylation has been shown to be associated with...
21:24
Methylated DNA Immunoprecipitation
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Cited by 43 •
2009
This video demonstrates the protocol for methylated DNA immunoprecipitation (MeDIP). MeDIP is a two day procedure that selectively extracts methylated DNA fragments from a genomic DNA sample using antibodies with specificity for 5 -methylcytosine (anti-5 mC).
01:10
Line Loss
0 Views •
2024
The different configurations of source-load connections include wye (star) and delta connections. The relationship between line and phase voltages and currents varies depending on the configuration. When the source is supplying power, it is transmitted through the wires to the load, and during this transmission, some power is absorbed by the wires, leading to line loss. Line loss impacts power delivery efficiency in a balanced three-phase circuit. The symmetry in such a circuit simplifies the...
12:34
DNA Methylation: Bisulphite Modification and Analysis
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Cited by 75 •
2011
The gold standard for DNA methylation analysis is genomic sequencing of bisulphite converted DNA. This method takes advantage of the increased sensitivity of cytosine compared with 5-methylcytosine (5-MeC) to bisulphite deamination under acidic conditions. Unmethylated cytosines can be distinguished from methylated cytosines after PCR amplification of the target genomic DNA.
12:27
Piping Networks and Pressure Losses
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2023
Source: Alexander S Rattner, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA This experiment introduces the measurement and modeling of pressure losses in piping networks and internal flow systems. In such systems, frictional flow resistance from channel walls, fittings, and obstructions causes mechanical energy in the form of fluid pressure to be converted to heat. Engineering analyses are needed to size flow hardware to ensure...
FAQs
Charge location helps determine which bonds are most susceptible to cleavage after ionization. When the charge is positioned in a way that supports breaking the bond attached to a methyl substituent, formation of the lower-mass product ion becomes more favorable. Interpreting that product therefore requires considering both the observed mass change and the likely location of charge within the precursor ion.
Methyl loss does not occur independently of molecular architecture. The strength of the bond connecting the methyl substituent, together with the surrounding structure, influences whether cleavage can occur during fragmentation. Consequently, two related molecules may produce different product-ion patterns even when both contain methyl groups, making structural context essential when assigning a methyl-loss pathway.
A product ion produced after methyl-group cleavage has a lower mass than its precursor ion, and the corresponding mass difference can indicate methyl substitution. Comparing this feature among related compounds can reveal whether their structures differ in methyl content or placement. The evidence is strongest when the observed fragmentation also agrees with the molecule’s charge location and bonding arrangement.
Analysis begins by examining the ionized molecular species and identifying its precursor mass. In tandem mass spectrometry, the precursor is fragmented and the resulting product ions are compared with the original ion. A lower-mass product showing the characteristic difference associated with methyl-group cleavage is then evaluated against charge location, bond strength, and molecular structure before assigning the pathway.
Methyl loss provides a fragmentation clue rather than a complete structural assignment by itself. The product-ion mass and the route proposed for its formation can support evidence for a methyl substituent and help evaluate alternative structures. Combining this clue with the precursor ion and other structural features improves interpretation of mass spectra and the distinction between related molecules.
In organic and analytical chemistry, observing methyl loss can indicate how a molecule fragments or changes under the conditions that generate the analyzed species. Researchers can use the resulting lower-mass ion to examine which bond was cleaved and how molecular structure influenced that event. This connects spectral observations with proposed reaction or fragmentation pathways.