This secondary antibody allows the detection of IgG2 and 3 from llamas and other camelids. It was produced in vitro and purified using protein G. It has low to no crossreactivity toward IgG1. This antibody is conjugated to R-Phycoerythrin (R-PE), a fluorescent protein isolated from red algae, and belonging to the phycobiliprotein family. Its primary absorption peak is at 565 nm with secondary peaks at 496 and 545 nm. The broad excitation spectrum of R-PE provides the advantage for multi-color immunofluorescent staining or cell sorting. R-PE and the closely related BPE are the most intensely fluorescent phycobiliproteins having orange fluorescence with maximum emission at 578 nm. They are significantly brighter and more photostable than conventional organic fluorophores. The degree of substitution (DOS) of this antibody conjugate is batch dependent and reported on the certificate of analysis.
Besides the conventional IgGs (IgG1, composed of heavy and light chains), llamas and other camelids produce single chain IgGs (IgG2 and IgG3). They are composed of heavy chains only and are lacking the light chains and the CH1 domains. The antigen binding domain of IgG2 and IgG3, called VHH, is the smallest naturally occurring antibody binding domain.