Protein purification from cells or supernatants, endogenous proteins complex analysis, and targeted protein enrichment for even more sensitive mass spectrometry-based biomarker discovery requires a particular immunoassay called immunoprecipitation (IP). Basically, the most robust method to pull-down a specific protein with its partners from cell lysates should be the combination of an antibody conjugated to biotin and magnetic beads with streptavidin. Unfortunately, if your antibody is not yet conjugated to biotin, conjugation is a blind process. That is why, using protein A/G coated sepharose beads is the most popular method.

But what if an antibody biotin conjugation kit could provide simple UV-scan based quantification of the conjugation yield?