Antibody, constant fragment

Constant Fragment (Fc) This is the stem of the letter Y. It is the part that is identical for all antibodies of the same class for example, all IgGs have the same Fc. The Fc fragment is the part that links the antibody to other receptors and triggers immune response and antigen destruction. 

Figure 32.3. The structure of the antibody molecule. All immunoglobulins consist of a basic subunit made up of four polypeptide chains (two light and two heavy) bound together by disulfide bonds. The variable region of the molecule contains the antigen binding site. Papain digestion yields a constant fragment (Fc) and variable fragments (Fab).

Antibodies not only recognize and bind to antigens, but they also direct the process by which the antigens are eliminated or killed. These are called the effector function. The base of the heavy chain (called the constant fragment, Fc) is species-... 

The affinity and cross-reactivity of the whole serum and Fab fragments were determined using equilibrium dialysis for the affinity determination and RIA for the cross-reactivity studies. The average intrinsic affinity constant (Ko) of the antibody (Nisonoff and Pressman 1958) changed very little throughout the... 

Fig. 15.1 Antibodies and antibody fragments produced in plant systems. A- In the conventional IgG, the constant heavy-chain CHI,...

BPE-phenytoin donor or phenytoin in a sample is bound by biotinylated antiphenytoin antibody. The donor is quenched by a Texas Red-avidin acceptor. The assembly is small enough to fit into a 23-gauge needle. Cycle time is from 5 to 30 min, with excellent reproducibility. The sensor has been further optimized and the reagents have been characterized by the determination of association and dissociation constants/120, 121) Intact antibody as well as Fab fragments are used, resulting in a sensor which responds well over the clinically useful concentration range of phenytoin. 

The Protein Profiling Biochip is composed of six chips assembled in a flow cell cassette device. Each chip provides 200 data points (200 pillars per chip) for a total of 1200 data points per cassette. Pillars are 50 p in diameter. The mesa on each pillar is covered with a self-assembled monolayer (20 to 25 A thickness) of biotin-derivatized PLL-g-PEG groups. A constant grafting ratio of 3.5 parts Lys to 1 part PEG is maintained with variable biotin-PEG content. sAV antibody is immobilized at 0.5 to 2 pmole/cm and Fab fragments at 4 pmole/cm. ... 

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