Backbone breakage

Fig. 5. Fragmentation nomenclature of peptides. Bond breakages of all bonds of the peptide backbone have a systematic name (I). When fragmenting multiply charged peptide ions the peptide bond breaks preferentially since it is among the most labile bonds and only relatively low collision energies are involved (II).

Backbone chain scission degradation can be divided as occurring via depolymerization, random chain breakage, weak-link or preferential site degradation, or some combination of these general routes. In depolymerization, monomer is split off from an activated end group. This is the opposite of the addition polymerization and is often referred to as unzipping. ... 

An alternative method to investigate DNA strand breakage by OH radicals considers the surface accessibility of hydrogen atoms of the DNA backbone [102]. The solvent accessibility is 80% for the sugar-phosphates and —20% for the bases. This method allows a more direct determination of reaction of OH radicals with the individual deoxyribose hydrogens [103,104]. Recent studies show trends in reactivity of OH radicals closely follow the accessibility of the solvent to various deoxyribose hydrogens [105,106]. 

Interference with these processes could clearly result in breakage in one or both chains of the DNA molecule, which it is now accepted forms the backbone of the chromatid. Large deletions may also occur after breakage of the chromosome if the repair processes are compromised. 

Free fatty acids indicate the breakage of the ester bond between the fatty acid and the glycerol backbone, releasing the fatty acid (Fig. Dl.4.2). The breakage of the ester bond can occur due to the presence of lipases, as found in damaged seeds, or as the result of hydrolytic... 

Cleavage of nucleic acids refers to a reaction that results in the breakage of bonds in the phosphodiester backbone of a polynucleotide chain. There are two types of reactions resulting in the cleavage of either P-O or C-O bonds in the nucleic acid backboue (see Figure Id). Cleavage of the P-O bond occurs as a result of uucleophilic attack ou the phosphorus atom via either an intermolecular reaction with a H2O molecule hydrolysis) or an intramolecular reactiou involving the ribose 2 -OH transesterification). Of these two reactions, transesterification is specific to RNA (since DNA lacks a 2 -OH moiety) and can be catalyzed by many M- +... 

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