Antibody Precipitation

When I mix the reduced antibody solution with the SMCC-XLAPC reagent a precipitate forms.

Most antibodies and many other proteins will give some precipitation when conjugated with the SMCC-xlAPC. Small amounts of precipitate can simply be removed by micro-centrifugation. If the amount of precipitation is unacceptably large, increase the ratio of SMCC-xlAPC to antibody. This can be accomplished by adding less antibody to the reaction or by adding more SMCC-xlAPC reagent.

Most antibodies will produce acceptable conjugates using 1.5 mg of SMCC-xlAPC per mg of reduced antibody in the conjugation protocol. Addition of 3 mg of SMCC-xlAPC per mg of reduced antibody will greatly reduce the amount of precipitate formed. Keep in mind, however, that increasing the SMCC-xlAPC in the reaction will also produce a conjugate with larger amounts of unconjugated xlAPC.