Dimers antibody

Grant, S., A. Porter, and W. Harris (1999). Comparative sensitivity of immunoassays for haptens using monomeric and dimeric antibody fragments. J. Agric. Food Chem., 47 340-345. 

Some growth factors act by binding two receptor molecules and causing the receptor to dimerize. Antibodies, with two identical binding sites, could similarly cause receptor dimerization and initiate the signaling process. 

Additional evidence for heterogeneity was obtained by fractionating the antidextran antibody population (16). The antibodies were bound to an immunosorbent and eluted successively with the dimer, isomaltose, or the trimer, followed by the hexamer. Precipitin reactions of antibodies eluted by the hexamer were not at all inhibitable by the dimer, whereas reactions of antibodies eluted with the dimer or trimer could be inhibited to some extent by the glucose dimer. Antibodies eluted by the trimer reacted equally weU with the pentamer and the hexamer. These results were taken to indicate that antibodies eluted by the smaller glucose... 

Fig.4. Competition ELISAbetween antibody 10D5 and viologen dimer 2.Anmnber of antibody molecules are immobilized on the ELISA plate at lower concentrations of viologen dimer 2...

Fig.Sa-f. The sensorgram of the repeated injection of the aqueous viologen dimer 2 (a, c, e) and the antibody (b, d, f) solutions. [Viologen dimer 2]=2.0 pM and [antibody]=2.0 pM in phosphate borate buffer. Injection period 60 s for a-c and 120 s for d-f. A solution of viologen dimer 2 or the antibody passes over the surface of the sensor chip for 60 or 120 s at a constant flow rate of 20 pL min. The surface of the sensor chip was subsequently washed with buffer...

The binding of the antibody is size-dependent. Only the preincubation of the antibodies with oligopectates of degree of polymerization (DP) > 9 inhibits the binding to pectin immobilized in the wells of an ELISA test (Fig. 9.a, b). The difference between dimerized DPS and DP9 oligomers lies in the fact that dimerized DP9 could accommodate five calcium ions between their two chains whereas DPS could only four, which is apparently insufficient for the complexes to resist thermal agitation. 

The association of two DP9 chains creates more than one epitope per dimer since after incubation with the 2F4 antibodies, the complexes precipitate on centrifugation. In other words, the 2F4 epitope must be much smaller than dimerized DP9. 

Antibody A52 with its epitope at residues 657-672 [129,139,274,275] inhibited the vanadate-induced crystallization of Ca " -ATPase and decreased the stability of preformed Ca " -ATPase crystals [285]. The vanadate-induced crystals arise by the association of the ATPase monomers into dimers (type A interaction), the dimers into dimer chains (type B interaction), and the dimer chains into 2-dimensional arrays (type C interaction). It is suggested that antibody A52 interferes with type B interactions, preventing the formation of dimer chains, without exerting major effect on the concentration of Ca -ATPase dimers in the membrane. The simplest interpretation of the destabilization of Ca -ATPase crystals by mAb A52 is that binding of the antibody to its antigenic site physically blocks the interaction between ATPase molecules [285]. Considering the large bulk of the antibody, such interference is not unexpected, yet only a few of the antibodies that bind to the Ca -ATPase in native sarcoplasmic reticulum interfered with crystallization. 

Tc-SOD-1) has been cloned and expressed (Matzilevich et al., 1999, unpublished results). While antibodies to this protein recognize a dimer of 20/22 kDa in larval extracts, evidence has yet to be obtained that this gene product is represented in larval TES. In addition, several more SOD genes have been identified by an EST project from a cDNA library from this stage. It seems likely, but has yet to be demonstrated, that SODs represent an important part of the parasite s defence mechanism against immune attack, as has been shown for other nematodes (James, 1994 Ou et al, 1995). 

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