Proteolytic enzymes immunoglobulin

Do not store ascitic fluids at 4°C, because they contain proteolytic enzymes, which will digest immunoglobulin at this temperature. Always store aliquots at -20 or—70°C... 

As with other pre-treatment methods, procedures for proteolytic pre-treatment vary due to laboratory-specific differences in formalin fixation. Proteolytic pre-treatment must be optimized (dilution and time — specific elevated temperature may also be selected) according to the particular fixation process used in each laboratory. Examples of antigens most often treated with proteolytic enzymes include cytokeratins and immunoglobulins. 

B cells and B-LCL express surface immunoglobulin and this can be exploited to select cells secreting antibody with the desired specificity. For blood group antibodies, sterile red cells of the appropriate blood group are conveniently used. If the antigen is resistant to proteolytic enzymes (papain, bromelain, tiypsin) these can be used to reduce the surface charge of the cells which enhances contact with B cells. 

IgG consists of four polypeptide subunits held together by disulphide bonds. Native immunoglobulins are rather resistant to proteolytic digestion but certain enzymes have been usefiil in elucidating their structure. Papain cleaves the molecule into three fragments of similar size ... 

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