Antibodies SMCC activated

Use of sulfo-NHS-LC-SPDP or other heterobifunctional crosslinkers to modify PAMAM dendrimers may be done along with the use of a secondary conjugation reaction to couple a detectable label or another protein to the dendrimer surface. Patri et al. (2004) used the SPDP activation method along with amine-reactive fluorescent labels (FITC or 6-carboxytetramethylrhodamine succinimidyl ester) to create an antibody conjugate, which also was detectable by fluorescent imaging. Thomas et al. (2004) used a similar procedure and the same crosslinker to thiolate dendrimers for conjugation with sulfo-SMCC-activated antibodies. In this case, the dendrimers were labeled with FITC at a level of 5 fluorescent molecules per G-5 PAMAM molecule. 

Figure 20.5 Antibodies may be modified with 2-iminothiolane at their amine groups to create sulfhydryls for conjugation with SMCC-activated enzymes. The maleimide groups on the derivatized enzyme react with the thiols on the antibody to form thioether bonds.

Conjugation of SMCC-Activated Antibody with Thiolated Toxin... 

Mix the thiolated toxin with SMCC-activated antibody at a ratio of 2.25 mg of antibody per mg of toxin. Protect the solution from light. 

Dissolve the enzyme to a concentration of 1 - 2 mg/ml in Soln. A (if it is delivered in another buffer, dialyze against Soln. A). Mix 1 mg -galactosidase in Soln. A with 0.25 mg SMCC activated antibody (concentration about 1 mg/ml for activation see Protocol 4.1.3). Shake at RT for 2 h, dialyze or desalt on a Sephadex G-25 column against Soln. B and concentrate to about 2 mg/ml. Mix 9 vol. of the concentrated conjugate with 1 vol. Soln. C and store without further purification at 4 °C. 

SMCC frequently is used to prepare hapten-carrier or antibody-enzyme conjugates. In both applications, one of the molecules is activated (usually the carrier or the enzyme) with the... 

The following is a generalized protocol for the activation of a protein with sulfo-SMCC with subsequent conjugation to a sulfhydryl-containing second molecule or protein. Specific examples of the use of this crosslinker to make antibody-enzyme or hapten-carrier conjugates may be found in Chapter 20, Section 1.1 and Chapter 19, Section 5, respectively. 

Figure 20.3 The reaction of SMCC with the amine groups on enzyme molecules yields a maleimide-activated derivative capable of coupling with sulfhydryl-containing antibody molecules.

Figure 21.13 Sulfo-SMCC may be used to activate antibody molecules for coupling to thiolated toxin components. An intact A-B toxin molecule can be modified to contain sulfhydryls by treatment with 2-iminothiolane. Thiolation with this reagent retains the cytotoxic properties of the toxin while generating a sulfhydryl for conjugation. Reaction of the thiolated toxin with the maleimide-activated antibody creates the immunotoxin through thioether bond formation.

Dialyze an antibody solution against Soln. C and concentrate to 20-30 mg/ml. Add 3 mg of sulfo-SMCC (3-sulfosuccinimidyl-4-(N-maleimidomethyl)-cyclohexane-l-caboxylate, Mr 436.7) or of sulfo-GMBS (N-(y-maleimidobutyryloxy)-3-sulfo-N-hydroxysuc-cinimide ester, Mr 382.3), dissolved in ddH20 to 60 mg/ml, to 10 mg of antibody, rock at RT for 15 min and add further 3 mg of coupling reagent. Desalt on a Sephadex G-25 column, equilibrated with Soln. A, after total incubation time of 30 min and use the activated antibody (protein) for conjugation immediately (see above). 

One note should be mentioned before proceeding when conjugating antibody molecules with (B-galactosidase, the antibody usually is activated with sulfo-SMCC first to take advantage of the indigenous sulfhydryl groups on the enzyme. Therefore, if (3-gal is being used, substitute the antibody for the enzyme mentioned in this protocol,... 

Antibody conjugates with GO can be made using the cross-linking agents glu-taraldehyde (Chapter 10, Section 1.2) or SMCC (Chapter 10, Section 1.1). The heterobifunctional reagent SMCC provides the best control over the conjugation process and usually results in high-activity preparations. 

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