Pepsin digestion

Figure 20.12 F(ab )2 fragments produced by pepsin digestion of IgG can be reduced at their heavy chain...

Recently, Noort et al developed a procedure that is based on straightforward isolation of adducted BuChE from plasma by means of affinity chromatography with a procainamide column, followed by pepsin digestion and LC/electrospray tandem MS analysis of a specific nonapeptide containing the phosphonylated active site serine-198 residue (5). This method surpasses the limitations of the fluoride-reactivation method, since it can also deal with dealkylated ( aged ) phosphonylated BuChE. The method allowed the positive analysis of several serum samples of Japanese victims of the terrorist attack in the Tokyo subway in 1995. Furthermore, the method could be applied for detection of ChE modifications induced by, e.g., diethyl paraoxon and pyridostigmine bromide, illustrating the broad scope of this approach. This new approach... 

F(ab )2 fragments of antibodies are generated by pepsin digestion of whole IgG antibodies to remove a portion of the Fc region (see Sect. 1.1). Elimination of nonspecific binding of the Fc region of antibodies to Fc receptors on cell surfaces in... 

Pepsin digestion generates Fab2 fragment and Fc fragment... 

Foaming Capacity and Stability. Pepsin digestion of soy protein has been proposed as a method for making a whipping protein for egg albumen replacement (42, 45) and for extenders for albumen in bakery and confectionery formulations (46). Puski... 

Epstein, E. H. [a 1 (III)] 3 human skin collagen. Release by pepsin digestion and preponderance in fetal life. J. BioL Chem. 249, 3225 (1974)... 

The prime character ( ), as in F(ab )2 and Fab, indicates that the fragments have been produced by pepsin digestion... 

Paraffin sections (6 p,m thick) of formalin-fixed tissues are mounted onto silanized glass slides and air-dried at 60°C (Henke and Ayhan, 1994). They are deparaffinized, rehydrated, and air-dried. The slides are placed in aplastic Coplinjar filled with lOmM sodium citrate buffer (pH 6.0) and microwaved (720 W) for 1 min this time is measured after reaching the boiling point. After treating with 1 M sodium thiocyanate for 10 min at 80°C, the sections are washed with distilled water and then digested with pepsin (3mg/ml in 0.2 N HC1) for 6 min at 37°C. Both the heating and the pepsin digestion durations must be... 

Fig. 2. Papain digestion of an antibody molecule yields two univalent Fab fragments and an Fc fragment whereas pepsin digestion yields a bivalent F(ab )2 fragment.

Maly et al. (1980) irradiated E. coli 50 S ribosomes and found that protein L4 was specifically crosslinked to the 23 S RNA. Again a 1 1 adduct was isolated, and after pepsin digestion, label was found in two peptides. Amino acid analysis showed that the peptides were similar and that a Tyr residue (residue 45 of L4) was altered. In one peptide the altered residue was N-terminal and in the second peptide the residue was the fifth and modified differently from that in the first peptide, in such a way that Edman degradation was blocked. 

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