Fragmentation sites

Finally, the follow-up cleavage can be described as changing from a simple decay, where the unpaired electron is mostly located at the fragmentation site, to an intramolecular ET that now occurs from the aryl-substituent system to the S—S a orbital, particularly with the nitro-substituted compound. The observed change in the ET rate would thus monitor a change in the overall ET-bond fragmentation mechanism. 

The method yields an exact solution to the problem on adsorbed -molecule distribution over a finite number of fragment sites. The maximum number of surface sites is limited from above and equals the number of fragment sites. A full set of topologies of a given fragment consists of all possible arrangements of dissimilar sites. 

Bik inhibitory strength and selectivity for serine proteases vary greatly with peptide sequence and posttranslational modifications such as fragmentation and glycoconjugation [6, 14, 15]. Predicted Bik fragmentation sites via trypsin binding and/or hydrolysis are shown (Fig. 2). 

FIGURE 1. Schematic representation of the pyrolysis of a phenol-formaldehyde resin, showing possible fragmentation sites leading to simple aromatic products... 

Fig. 13. Major fragmentation sites of sphingolipids that are useful for analysis by electrospray tandem mass spectrometry [6].

Li L, Olafsen T, Anderson A L, et al. (2002). Reduction of kidney uptake in radiometal labeled peptide linkers conjugated to recombinant antibody fragments. Site-specific conjugation of DOTA-peptides to a Cys-diabody. Bioconjug. Chem. 13 985-995. 

Figure 4.2 MS fragmentation of oligonucleotides. Four possible fragmentation sites of oligonucleotides and their proposed nomenclature are depicted...

Fig. 2. Panel A Structure of some common glycerophospholipids and the typical fragmentation sites. Panel B Structure of some common sphingoUpids and typical fragmentation sites. Panel C Structure of acylglycerols, cholesterol, and cholesterylesters.

Locating Favourable Positions of Molecular Fragments Within a Binding Site... 

In one instrument, ions produced from an atmospheric-pressure ion source can be measured. If these are molecular ions, their relative molecular mass is obtained and often their elemental compositions. Fragment ions can be produced by suitable operation of an APCI inlet to obtain a full mass spectrum for each eluting substrate. The system can be used with the effluent from an LC column or with a solution from a static solution supply. When used with an LC column, any detectors generally used with the LC instrument itself can still be included, as with a UV/visible diode array detector sited in front of the mass spectrometer inlet. 

Determination of DNA Sequence Information. Almost all DNA sequence is determined by enzymatic methods (12) which exploit the properties of the enzyme DNA polymerase. Whereas a chemical method for DNA sequencing exists, its use has been supplanted for the most part in the initial deterrnination of a sequence. Chemical or Maxam-Gilbett sequencing (13) is mote often used for mapping functional sites on DNA fragments of known sequence. 

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