Labeling Chemistry

Protein labeling reagents are used for various assays that are coupled with antigen-antibody reactions. Of these, fluorescent, biotin, and enzyme labeling reagents are used most frequently for antibody labeling. Most protein labeling reagents have similar reactive sites, such as succinimidyl ester (NHS) for amino groups and maleimide or bromoacetamide for sulfhydryl groups. Dojindo offers a wide variety of protein labeling kits. These kits can be used to prepare conjugates with enzymes, fluorophore, and biotin. Dojindo’s labeling kits contain centrifugal filtration tubes, which are used for protein purification, conjugation reaction, condensation, and buffer exchange.
Our newest addition, Ab-10 Rapid Labeling Kits allows simple and rapid preparation of enzyme or fluorophore conjugates with a smaller quantity of antibody.

Table1 Antibody labeling procedure comparison

*Ab-10:Some additives in the antibody solution may interfere with the labeling if the concentration is too high. The maximum compatible concentrations of such additives are indicated in on Table 2.

Table 2 Compatible concentrations of the additives

What are Cross-Lining Reagents ?

Cross-Linking Reagents are widely used for both immune assays and protein analysis. Dojindo offers a variety of reagents that have different spacer arm lengths or functional groups. The two different types are:

1. Hetero-bifunctional Reagents contain different reactive groups on each end of the spacer arm. Dojindo offers the reagents which have a NHS ester group (amine reactive) and a maleimide group (sulfhydryl reactive) on each end. They can be used for binding proteins that have sulfhydryl groups (such as Fab’) to enzymes such as POD and ALP.
2. Homo-bifunctional Reagents contain the same reactive group on both ends of the spacer arm. Dojindo offers reagents that have 2 NHS ester groups. They can be used to bind proximate proteins or to introduce NHS ester group to compounds that have amino groups.