Confirmation of covalently-linked structure and cell-death inducing activity in site-specific chemical conjugates of human Fas ligand extracellular domain

Objective In this study, we aimed to identify the structural components and to clarify the biological activity in the site-specific conjugates of human Fas ligand extracellular domain (hFasLECD) with either fluorescein moiety (FL) or chicken egg-white avidin (Avi). The conjugates were characterized by molecular-weight measurement using MALDI-TOF mass-spectrometric analysis and by cell-death inducing activity measurement against a human colorectal cancer cell line, HT-29, using MTT cell-viability assay. Pretreatment effect with human interferon-γ (IFN-γ) on the cell-death inducing activity was evaluated.