title: A quantitative assessment of glycolipid and protein associated with paired helical filament preparations from Alzheimer's diseased brain.
abstract: Protease resistant paired helical filaments (prcPHF) can be isolated from the brains of Alzheimer's diseased patients. A second type of PHF, A68 PHF, may be extracted in soluble form from brain homogenate and induced to form filaments in vitro. Here we use a variety of analytical techniques to assess the protein, carbohydrate and fatty acid composition of prcPHF and A68 PHF. High-field ^1H NMR of both PHF preparations display similar fatty acid and carbohydrate proton resonances, consistent with the presence of a structurally similar glycolipid. Carbohydrate analysis showed that both preparations contained greater than 82% less than 12% C16:1 was significantly lower in A68 PHF than in prcPHF, both preparations contained otherwise similar fatty acid profiles with the most abundant lipid component being oleic acid (C18:1, 29.3 +/- 9.0%) followed by palmitic (C16:0, 28.5 +/- 5.6%) 17.6 +/- 7.5%) preparations revealed a profile reasonably consistent with that previously determined for PHF-tau but significantly higher in glycine and lower in lysine than would be predicted from the cDNA sequence. On a weight per cent basis, protein accounted for about 51% A68 PHF samples but only about 10% Carbohydrate and fatty acid accounted for about 39% A68 PHF samples but 74% preparations showed strong correlations between the total amount of tau protein and fatty acid. These results suggest that a glycolipid component forms an integral part of the PHF structure.
authors.affiliation: Department of Chemistry, University of Texas at Dallas, P.O. Box 830688, Richardson, TX 75083-0688, USA.
authors.forename: Warren J.
authors.initials: WJ
authors.lastname: Goux
authors.forename: Bingcam
authors.initials: B
authors.lastname: Liu
authors.forename: Abdurahman M.
authors.initials: AM
authors.lastname: Shumburo
authors.forename: Samir
authors.initials: S
authors.lastname: Parikh
authors.forename: Dennis R.
authors.initials: DR
authors.lastname: Sparkman