Preparative separation and amino acid composition of neurofilament triplet proteins

Intact neurofilaments were isolated from bovine spinal cord white matter, washed by sedimentation in 0.1 M-NaCl, and extracted with 8 M-urea. Solubilized neurofilament triplet proteins of molecular weights approximately 68,000 (P68), 150,000 (P150), and 200,000 (P200) were purified by preparative electrophoresis, using an LKB 7900 Uniphor apparatus. The method provides for an enhanced yield of purified protein and has markedly reduced admixture of electrophoresed protein with acrylamide and associated protein contaminants. Amino acid compositions of the purified neurofilament triplet proteins are reported and compared.