Fig. 3.
The abundance of free sulfhydryl groups is greater in proteins from riboflavin-deficient HepG2 cells (“Def.” = 3.1 nmol/L riboflavin) compared with riboflavin-sufficient controls (“Control” = 532 nmol/L riboflavin). Cells were cultured in riboflavin-defined media for 4 d. Sulfhydryl groups in proteins from cell extracts were derivatized with polyethylene oxide-iodoacetyl biotin; plasminogen was visualized by Western blot analysis using an antibody to human plasminogen. Commercial, chemically pure plasminogen (with and without pretreatment with dithiothreitol) was used as a control. N/A = not applicable.