pHAb Amine and Thiol Reactive Dyes are sensor dyes that have very low fluorescence at pH >7 and a dramatic increase in fluorescence as the pH of the solution becomes acidic.

pHAb Reactive Dyes are designed specifically for labeling antibody, and are available in two reactive forms suitable for antibody conjugation. pHAb Amine Reactive Dye has a succinimidyl ester group that reacts with primary amines available on the lysine amino acids on the antibodies (Figure 1, Panel A). pHAb Thiol Reactive Dye has a maleimide group that reacts with thiols. This maleimide group is conjugated to the antibody after the cysteine disulfide bonds in the hinge region of the antibody are reduced to thiols through the use of a reducing agent, such as DTT or TCEP (Figure 1, Panel B). pHAb Reactive Dyes retain their fluorescent response to decreases in pH even after conjugation to antibody.

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