Partial Separation and Some Kinetic Studies of Ceruloplasmin in Human Serum

The study attempts to isolate the enzyme ceruloplasmin from human serum. Two proteinous components had been isolated by gel filtration chromatography from the precipitate produced by polyethylene glycol (4000). It was found that only the second peak had a high activity for ceruloplasmin. The apparent molecular weight of the isolated ceruloplasmin using gel filtration chromatography and SDS-PAGE was (138111) and (134400) dalton respectively.
Maximum activity for ceruloplasmin was obtained using (35.8) mmol/l of p-phenylenediamine as a substrate for the enzyme, sodium acetate (0.1 mol/l) as a buffer at pH (5.45) for (35) minutes at (56) C. Using lineweaverburk plot, it was found that maximum velocity (Vmax) and Michaelis constant (Km) had the values of (0.83) mol/ min and (15.38) mmol/l respectively. The effects of some chemical compounds on the ceruloplasmin activity were investigated. Sodium chloride showed uncompetitive inhibition on the activity of the enzyme at a concentration of (70) mmol/l.