title: Determination of the sedimentation coefficient and molecular weight of proteins by density gradient ultracentrifugation in fixed angle rotor.
abstract: The applicability of density gradient ultracentrifugation using fixed angle rotors for the determination of sedimentation coefficient and molecular weight of proteins was studied. Ovalbumin, bovine serum albumin, IgG-, IgA- and IgM-globulin proteins, as standards were, among others, centrifuged in a fixed angle rotor (Beckman type 50) in 5-20% (w/v) sucrose density gradient for 300 min, at a speed of 40,000 rpm, at 5 degrees C. After centrifugation, the sedimentation diagram of the above-mentioned proteins was taken by a spectrophotometer equipped by a flow-through cuvette and a compensator. The sedimentation path was measured on the diagrams. A calibration curve was drawn by plotting the sedimentation coefficients of the standard proteins against the sedimentation paths. This curve, for which the equation y = 1.74x-1.6 is valid, was used for the determination of the sedimentation coefficients of several globular proteins under the conditions described above. The values obtained this way agree within +3-10% with those determined with analytical ultracentrifuge. If the logarithms of proteins molecular weight used as standards were drawn against the logarithms of their sedimentation paths a calibration curve was obtained. This curve for which the equation ln y = 2.022 ln x + 8.71 is valid can be used for the determination of molecular weights of globular or nearly globular proteins.
authors.affiliation: Central Research Laboratory, University Medical School, Debrecen, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Szabolcs
authors.forename: I
authors.initials: I
authors.lastname: Francia
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient / Q000379:methods*; D005903:Gliadin / Q000737:chemistry; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D008970:Molecular Weight; D007296:Myo-Inositol-1-Phosphate Synthase / Q000737:chemistry; D010763:Phosphorylase b / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011817:Rabbits; D012710:Serum Albumin, Bovine / Q000737:chemistry; D014168:Transferrin / Q000737:chemistry
chemical_list: D007136:Immunoglobulins; D011506:Proteins; D014168:Transferrin; D012710:Serum Albumin, Bovine; D005903:Gliadin; D010763:Phosphorylase b; D007296:Myo-Inositol-1-Phosphate Synthase