title: Preparation of the proteolipid apoprotein from bovine heart, liver and kidney.
abstract: Proteolipid apoproteins have been prepared from heart, kidney, and liver by dialysis in chloroform/methanol against chloroform/methanol, acidified chloroform/methanol, and chloroform/methanol in succession. They are free of lipids (less than 0.05% P; less than 0.1% carbohydrate). They show a high content of non-polar amino acids, methionine, and tryptophan and contain little or no half-cystine. The differ from neural proteolipid apoproteins by absence of half-cystine, and of covalently bound fatty acids. As recovered from chloroform/methanol solutions, they are soluble in chloroform/methanol and insoluble in water, but a water-soluble form can be prepared by changing the solvent from chloroform/methanol to water in a stream of nitrogen. The chloroform-methanol-soluble form and the water-soluble form are interconvertible. ORD and CD spectra of all proteolipid apoproteins indicate 60-70% alpha-helix content in chloroform/methanol solution and 20-30% alpha-helix in water solution. Sodium dodecyl sulfate gel electrophoresis resolves proteolipid apoprotein into two major components corresponding to ca. 12 000 and 34 000 daltons. With sodium dodecyl sulfate/urea numerous bands appear, with a major one at 30 000 daltons and 8 to 10, ranging downward to 2500. For comparison, neural proteolipid apoproteins also show numerous bands with a major one at 25 000. The marked chemical and physical similarities among all proteolipid apoproteins studied suggest a common role in membrane structures.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001059:Apoproteins / Q000302:isolation & purification*; D001923:Brain Chemistry; D002417:Cattle; D002942:Circular Dichroism; D005227:Fatty Acids / Q000032:analysis; D007668:Kidney / Q000032:analysis*; D008074:Lipoproteins / Q000302:isolation & purification*; D008099:Liver / Q000032:analysis*; D008970:Molecular Weight; D009206:Myocardium / Q000032:analysis*; D009419:Nerve Tissue Proteins / Q000302:isolation & purification; D009905:Optical Rotatory Dispersion; D009928:Organ Specificity; D011487:Protein Conformation
chemical_list: D000596:Amino Acids; D001059:Apoproteins; D005227:Fatty Acids; D008074:Lipoproteins; D009419:Nerve Tissue Proteins