PFc fragments

The lack of binding of the pFc fragment (corresponding to the Ch3 domain of immunoglobulin G) or of the Facb derivative (which is derived from Ch3) of rabbit immunoglobulin to staphylococcal protein A, suggests that the locus of protein A binding is at the interface between the Ch2 and Ch3 domains. ... 

QMS would be very helpful in determining the amount of specific PFCs present in air [ 114,115]. In 1997, a QMS with an electron-impact ion source was used to measure PFC concentrations. The main disadvantage of this method may be the interference of ion signals due to the high probability of PFC fragmentation. This creates difficulty in quantitative analysis and the situation is further complicated as most of PFCs break into similar fragments. On-site cahbration is essential for analysis with a QMS. Therefore Hamisch et al. [116] employed MS combined with a GC and/or a cryotrap technique for the measurements of CF, SFg, and C2Fg in the atmosphere. 

Table 3.4 Ion fragments observed In the GC-MS analysis of PFCs. Pseudo molecular Ions are typically used for quantitation (indicated In bold)...

Figure 2. Human IgG, showing the location of the sites of cleavage of F(ab )s and Fc fragments as well as the Fc (papain) and pFc (pepsin) fragments (numbered from COOH-terminal ends of y chains). Carbohydrate is denoted by Cbh. Reproduced from Turner et al. (1969o) by courtesy of Dr. M. W. Turner and Nature.

Keywords CID Fragmentation Mass spectrometry Per- and polyfluorinated chemicals (PFC)... 

Modem instruments offer novel sophisticated modes to detect non-target analytes. If the fragmentation behavior of a compound class is known, this can be used to find derivatives of these compounds even though the sfructure of the complete molecule is unknown. If X represents the characteristic moiety of a compotmd class, which is attached to any moiety R, let us assume two hypothetic fragmentation pathways (fragmentation of anions is chosen because most PFC metabolites are ionized negatively) ... 

A fragment, designated stFc by Utsumi (81), is obtained by digestion of rabbit IgG with papain at pH 4.5. It has a molecular weight of 25,000 and contains only the C-terminal antigenic determinants of the molecule. The fragment, therefore, resembles human Fc or pFc. ... 

A variety of techniques have been developed to investigate protein-protein interactions in cultured cells, including the two-hybrid system and protein-fragment complementation (PFC). The two-hybrid system is the most widely applied method to identify and characterize protein interactions. However, several features of PFC make it attractive as an approach for in vivo imaging of protein interactions in cells, and particularly, in live animals. Subsequently, we describe major features of these two methods and other strategies with potential utility for in vivo imaging. 

PFC assays depend on division of a monomeric reporter enzyme into two separate inactive components that can reconstitute function upon association [Fig. 12.2(a)]. When these reporter fragments are fused to interacting proteins, reporter activity is reconstituted upon association of the interacting proteins. PFC strategies based on several enzymes including /3-galactosidase,... 

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