title: Conformational analysis of serum apolipoprotein AII in lipoprotein complexes with bifunctional crosslinking reagents.
abstract: Apolipoprotein AII isolated from human serum high density lipoproteins was recombined with phosphatidylcholine to yield homogeneous particles of 80-120 A diameter. The radioactive bifunctional crosslinkers dimethyl [1,1'-14C]suberimidate and dimethyl 4,4'-dithiobis([1-14C]butyrimidate) were reacted with these particles. The kinetics of the reactions and the localisation of the crosslinked lysines of the polypeptide chains were determined. Thermolysin hydrolysis followed by two-dimensional separation of the peptides and isolation of the mono- and bifunctionally modified peptides allowed the assignment of the crosslinked peptides of the apoprotein AII seqeunce. The crosslinking pattern indicates a close-neighbour relationship (13-15 A) of the peptide chains between amino acid residues 3, 23, 46 and 55 of the symmetrical halves of the apo AII molecule. A reconstruction of the secondary structure of Apo AII in the lipoprotein complex on the basis of theoretical calculations is given and correlated with the chemical data.
mesh_terms: D000595:Amino Acid Sequence; D001053:Apolipoproteins / Q000097:blood; D004120:Dimethyl Suberimidate; D006801:Humans; D007202:Indicators and Reagents; D007700:Kinetics; D008075:Lipoproteins, HDL / Q000097:blood; D008239:Lysine; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D010713:Phosphatidylcholines; D011485:Protein Binding; D011487:Protein Conformation; D013820:Thermolysin
chemical_list: D001053:Apolipoproteins; D007202:Indicators and Reagents; D008075:Lipoproteins, HDL; D046911:Macromolecular Substances; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D004120:Dimethyl Suberimidate; D013820:Thermolysin; D008239:Lysine