Toxin antibodies using SMPT

SMPT often is used in place of SPDP for the preparation of immunotoxin conjugates. The hindered disulfide of SMPT has distinct advantages in this regard. Thorpe et al. (1987) showed that SMPT conjugates had approximately twice the half-life in vivo as SPDP conjugates. Antibody-toxin conjugates prepared with SMPT possess a half-life in vivo of up to 22 hours, presumably due to the decreased susceptibility of the hindered disulfide toward reductive cleavage. 

Figure 21.8 SMPT may be used to form immunotoxin conjugates by activation of the antibody component to form a thiol-reactive derivative. Reduction of an A-B toxin molecule with DTT can facilitate subsequent isolation of the A chain containing a free thiol. Mixing the A-chain containing a sulfhydryl group with the SMPT-activated antibody causes immunotoxin formation through disulfide bond linkage. The hindered disulfide of an SMPT crosslink has been found to survive in vivo for longer periods than conjugates formed with SPDP.

Figure 322 SMPT may be used to form immunotoxin conjugates by activation of the antibody component to form a thiol-reactive derivative. Reduction of an A—B toxin molecule with DTT can facilitate subsequent...

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