Portal de Periódicos da CAPES

The reaction of 4,4′-difluoro-3,3′-dinitro-diphenyl sulfone with γ-globulin and horseradish peroxidase

1971; Elsevier BV; Volume: 229; Issue: 2 Linguagem: Inglês

10.1016/0005-2795(71)90197-8

1878-1454

Rosario R. Modesto, Amadeo J. Pesce,

Effects and risks of endocrine disrupting chemicals

1. The degree of intermolecular coupling of horseradish peroxidase and γ-globulin (immunoglobulin, IgG) was less than 1% at 4° with a single addition of 4,4′-difluoro-3,3′-dinitro-diphenyl sulfone (FNPS). The reaction was studied in full detail to establish optimal conjugating conditions. 2. Titration of horseradish peroxidase with FNPS, under optimal conditions, gave 1.6–1.7 moles of reagent bound per mole protein with retention of most of the enzymatic activity. Apoprotein after reaction with FNPS bound approx. 4.0 moles reagent per mole protein, suggesting that the heme prosthetic group of the enzyme blocked some lysyl residues from reacting. 3. Samples of IgG reacted more readily with FNPS and bound between 5–16 moles of reagent per mole protein, depending upon the concentration of reagent and reaction time. 4. Reaction mixtures containing both IgG and horseradish peroxidase showed 66-fold preferential binding of FNPS to IgG. Since IgG reacted well and polymerized, and since horseradish peroxidase did not dimerize and was structurally unchanged under optimal conditions of reagent addition, it was concluded that the poor yields of the conjugation were due to lack of reagent addition to the enzyme. 5. Since these antibody conjugates contain large amounts of polymerized IgG, they should be used with caution.