Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Structural and functional characterization of human apolipoprotein E 72-166 peptides in both aqueous and lipid environments | Hsieh and Chou Journal of Biomedical Science 2011 18 4 http content 18 1 4 The cost of publication in Journal of Biomedical Science Is borne by the National Science Council Taiwan JOURNAL OF BIOMEDICAL SCIENCE RESEARCH Open Access Structural and functional characterization of human apolipoprotein E 72-166 peptides in both aqueous and lipid environments Yi-Hui Hsieh Chi-Yuan Chou Abstract Backgrounds There are three apolipoprotein E apoE isoforms involved in human lipid homeostasis. In the present study truncated apoE2- apoE3- and apoE4- 72-166 peptides that are tailored to lack domain interactions are expressed and elucidated the structural and functional consequences. Methods Results Circular dichroism analyses indicated that their secondary structure is still well organized. Analytical ultracentrifugation analyses demonstrated that apoE- 72-166 produces more complicated species in PBS. All three isoforms were significantly dissociated in the presence of dihexanoylphosphatidylcholine. Dimyristoylphosphatidylcholine turbidity clearance assay showed that apoE4- 72-166 maintains the highest lipid-binding capacity. Finally only apoE4- 72-166 still maintained significant LDL receptor binding ability. Conclusions Overall apoE4- 72-166 peptides displayed a higher lipid-binding and comparable receptor-binding ability as to full-length apoE. These findings provide the explanation of diverged functionality of truncated apoE isoforms. Introduction Human apolipoprotein E apoE 1 comprises 299 amino acids and there are three isoforms apoE2 apoE3 and apoE4 encoded by the e2 e3 and e4 genes respectively. These isoforms differ from each other only at residues 112 and 158 . Cys112 and Arg158 in apoE3 a cysteine at both positions in apoE2 and an arginine at both positions in apoE4 1 . The amino-terminal NT domain of apoE contains four amphipathic a-helices and has pronounced kinks in the helices near the end of the four-helix bundle that correlates with
