Antibodies papain

Porter, R.R. Hydrolysis of rabbit gamma-globul in and antibodies with crystalline papain. Biochem J. 73 119-126, 1959. 

Figure 20.11 Papain digestion of IgG antibodies primarily results in cleavage in the hinge region above the interchain disulfides. This produces two heavy-light chain pairs, called Fab fragments, each containing one antigen binding site. The Fc region normally can be recovered intact.

Figure 1.8. Diagrammatic representation of an antibody molecule. An antibody molecule comprises two heavy chains (dark shading) and two light chains (unshaded). These chains are held together by disulphide (-S—S-) bonds. The site of papain cleavage (yielding Fab and Fc portions of the molecule) is shown. Each antibody molecule has two potential anti-gen-binding sites.

A family of 100 hybridoma antibodies can typically provide 20 tight binders and these need to be assayed for catalysis. At this stage in the production of an abzyme, the benefit of a sensitive, direct screen for product formation comes into its own. Following identification of a successful catalyst, the antibody is usually recloned to ensure purity and stabilization of the clone, then protein is produced in larger amount (—10 mg) and used for determination of the kinetics and mechanism of the catalysed process by classical biochemistry. Digestion of such protein with trypsin or papain provides fragment antibodies, Fabs, that contain only the attenuated upper limbs of the intact IgG (Fig. 1). It is these components that have been crystallized, in some... 

Moorehouse K.G., Nashabeh W., Deveney J., Bjork N.S., Mulkerrin M.G., and Ryskamp T. (1997), Validation of an HPLC method for the analysis of the charge heterogeneity of the recombinant monoclonal antibody IDEC-C2B8 after papain digestion, J. Pharm. Biomed. Anal. 16, 593-603. 

An antibody can be cleaved by enzymes such as papain and pepsin into different fragments (Fig. 4.2). 

This is a papaya enzyme available over the counter. It is not known whether this does anything. Dr. Grow said that Papain is an antibody to THC, and in theory may destroy THC when added to the urine sample. However, positive urine doesn t actually contain THC it contains THC byproducts. Papain has not been tested, and may or may not work. 

Since antibodies of different species and different subclasses are variably cleaved by pepsin and papain, a test run is recommended to check incubation time and cleavage conditions. Take samples of different incubation time, freeze rapidly, and monitor the fragmentation by SDS-PAGE at the end of the experiment. Apply the samples both with and without DDT. 

Chillproofers are added to freshly brewed beers to prevent the formation of haze upon cold storage. Papain-based enzymes have been used as chillproofers and their addition have to be monitored carefully, as overdosage results in flat beer. According to Skerritt et al (146), enzymatic methods currently used lack sensitivity or are slow and tedious. They have developed a polyclonal antibody-based kit for determination of these chillproofers. 

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.

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