Michael,
If you only need to know 150kD species vs. everything else, size exclusion
chromatography will do the job. A G4000SW works well for this. It is
usually not possible to assign meaningful MW's to the higher MW species
though.
Regards,
Dan L. Crimmins
Washington University School of Medicine
Dept. Pathology/Division of Laboratory Medicine
660 S. Euclid Ave., Box 8118
St. Louis, MO 63110
Phone: 314-454-8514; Fax: 314-454-5208
e-mail: crimmins@labmed.wustl.edu