LPL-mediated TG hydrolysis in VLDL fractions in whole plasma separated by size-exclusion chromatography. Citrated plasma (350 μl) was incubated with increasing amounts of recombinant human LPL in vitro and then separated by fast protein liquid chromatography (FPLC) over a Superose 6 gel filtration column in PBS as described in the Materials and methods section. About 300 μl fractions were collected, and TG was quantified colorimetrically. VLDL eluted within fractions 15–23 and LDL eluted in fractions 25–33 in this system. Orlistat, a lipase inhibitor, was used as a control and to quench the reactions. Samples include whole plasma without exogenous LPL (closed circle), whole plasma with 1.5 μg/ml LPL and 50 μM Orlistat (open circle), plasma with 0.37 μg/ml LPL (closed diamond), plasma with 0.75 μg/ml LPL (open downward triangle), plasma with 1.0 μg/ml LPL (closed upward triangle), and plasma with 1.5 μg/ml LPL (closed square). Experiments were performed in triplicate with representative traces shown.