Biomaterial Database

Structural and binding characteristics of the carboxyl terminal fragment of apolipophorin III from Manduca sexta. 1994

V Narayanaswami, and C M Kay, and K Oikawa, and R O Ryan

Lipid & Lipoprotein Research Group, University of Alberta, Edmonton, Canada.

The molecular basis of the interaction of apolipophorin III (apoLp-III), an exchangeable apolipoprotein from hemolymph of the sphinx moth. Manduca sexta, with lipoprotein surfaces and phospholipids was studied by investigating the structural and binding properties of the C-terminal fragment of the native protein. A 4K peptide, corresponding to the terminal helical segment of the native protein, was generated by cyanogen bromide treatment, purified by gel filtration and reverse-phase HPLC, and characterized by N-terminal sequencing and amino acid and mass spectrometric analysis. Circular dichroism (CD) spectroscopy of the peptide in buffer indicated a predominantly unstructured state while addition of trifluoroethanol (TFE), a helix-inducing agent, resulted in an alpha-helical structure. Sedimentation equilibrium studies revealed that the 4K peptide was monomeric in buffer. The 4K peptide assumed an alpha-helical conformation in the presence of sodium dodecyl sulfate (SDS) and lysolecithin, but was unstructured in the presence of dimyristoylphosphatidylcholine, either when added to preformed vesicles or upon cosonication, indicating an ability to bind to detergent micelles but not to phospholipid bilayers. Unlike native apoLp-III, the 4K peptide did not confer protection against turbidity development to human low density lipoprotein upon incubation with phospholipase C, indicating an inability to interact with the surface of lipoproteins. Upon interaction with SDS micelles, both the 4K peptide and apoLp-III were resistant to urea-induced denaturation when compared to free apoLp-III, as evaluated by CD spectroscopy. The structural stability conferred upon interaction with detergents was similar for both the peptide and the native protein.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008077	Lipoproteins, LDL	A class of lipoproteins of small size (18-25 nm) and light (1.019-1.063 g/ml) particles with a core composed mainly of CHOLESTEROL ESTERS and smaller amounts of TRIGLYCERIDES. The surface monolayer consists mostly of PHOSPHOLIPIDS, a single copy of APOLIPOPROTEIN B-100, and free cholesterol molecules. The main LDL function is to transport cholesterol and cholesterol esters to extrahepatic tissues.	Low-Density Lipoprotein,Low-Density Lipoproteins,beta-Lipoprotein,beta-Lipoproteins,LDL(1),LDL(2),LDL-1,LDL-2,LDL1,LDL2,Low-Density Lipoprotein 1,Low-Density Lipoprotein 2,LDL Lipoproteins,Lipoprotein, Low-Density,Lipoproteins, Low-Density,Low Density Lipoprotein,Low Density Lipoprotein 1,Low Density Lipoprotein 2,Low Density Lipoproteins,beta Lipoprotein,beta Lipoproteins
D008567	Membranes, Artificial	Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.	Artificial Membranes,Artificial Membrane,Membrane, Artificial
D008961	Models, Structural	A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)	Model, Structural,Structural Model,Structural Models
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia