The separation of sheep and human serum "A"-esterase activity into the lipoprotein fraction by ultracentrifugation.

Using sheep and human serum the relationship between centrifugation time and yield of total lipoprotein, HDL-cholesterol and "A"-esterase in lipoprotein was studied employing different centrifuge rotors. More rapid separation of these components was obtained with a vertical rotor than with an angled rotor. The procedures commonly employed for lipoprotein separation gave low yields of lipoprotein "A"-esterase and HDL-cholesterol. The separation of sheep serum "A"-esterase into the lipoprotein fraction was not in phase with that of HDL-cholesterol and the pattern of separation was different from that in human serum. These results provide further evidence that serum "A"-esterase activity is associated with different species of HDL-particle.