Disulfide bonds/linkages

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.

Chen et al. (2007) have developed a nanoinjector that injects compounds immobilized on MWNT-atomic force microscopy (AFM) tips into the cells. First, a MWNT-AFM tip was fabricated from a normal AFM tip with an MWNT on one end. Next, a compound of interest was immobilized on the MWNT-AFM tip through a disulfide bond linkage. After MWNT-AFM tip was tapped on the cell, the cantilever was further lowered and the MWNT nanoneedle then penetrated the membrane. Once inside the cell, the disulfide linkage was broken under the cells reducing environment and the compound of interest was released inside the cell. The MWNT-AFM tip was then removed from the cell. In this study, protein was... 

Fig. 6. Cysteine positions in the HCIIs. The cysteine positions of HCIIs are placed on a schematic diagram of HCII secondary structure. Helices are shown as rectangles and loops as lines. Experimentally determined and predicted disulfide bond linkages are shown.

Figure 4. Cyclic analog of the leucokinin active core (X - Tyr) with a disulfide bond linkage.

SMPT-activated antibody causes immunotoxin formation through disulfide bond linkage. The hindered... 

Trisulfide bonds, originally elucidated in human growth hormone," " were detected recently in mAbs at low levels.The linkage between light and heavy chain is the predominant location of trisulfide bonds in mAbs. Ironically, nonreducible thioether bonds were detected previously at this same disulfide bond linkage in mAbs via peptide map analysis." " ... 

Sanger also determined the sequence of the A chain and identified the cysteine residues involved m disulfide bonds befween fhe A and B chains as well as m fhe disulfide linkage wifhin fhe A chain The complefe insulin sfruefure is shown m Figure 27 11 The sfruefure shown is fhaf of bovine insulin (from cattle) The A chains of human insulin and bovine insulin differ m only fwo ammo acid residues fheir B chains are identical except for the ammo acid at the C terminus... 

Figure 6.3 Mts-Atf-Biotin can be used to label bait proteins at available thiol groups using the MTS group, which forms a disulfide linkage after reaction. The modified protein then is allowed to interact with a protein sample and photoactivated with UV light to cause a covalent crosslink with any interacting proteins. Cleavage of the disulfide bond effectively transfers the biotin label to the unknown interacting protein.

Figure 21.1 The basic design of an immunotoxin conjugate consists of an antibody-targeting component crosslinked to a toxin molecule. The complexation typically includes a disulfide bond between the antibody portion and the cytotoxic component of the conjugate to allow release of the toxin intracellularly. In this illustration, an intact A-B toxin protein provides the requisite disulfide, but the linkage also may be designed into the crosslinker itself.

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