Biomaterial Database

Fusion of phospholipid vesicles induced by alpha-lactalbumin at acidic pH. 1986

J Kim, and H Kim

Alpha-Lactalbumin (alpha-LA), lysozyme, and ribonuclease are found to induce fusion of phosphatidylserine/phosphatidylethanolamine vesicles at low pH. The fusogenic behavior and the binding to phospholipid vesicles of one of these proteins, alpha-LA, are studied at a wide range of conditions. The initial rate of fusion in the presence of alpha-LA increases with increasing acidity below pH 6, and the extent of alpha-LA binding to the vesicles is also found to increase with decreasing pH. Once bound to the vesicles in acidic media, the neutralization to pH 7 fails to dislodge the alpha-LA from the vesicles, and this irreversible binding also increases with decreasing pH. A segment of alpha-LA is found to be resistant to the proteolytic digestion when initially incubated with the vesicles at low pH. The amino acid composition of this fragment was determined, and from this the sequence of alpha-LA fragment, which appears to be inserted into the bilayer, is deduced. Hydrophobic labeling with dansyl chloride renders support that this segment indeed penetrates into the hydrophobic interior of bilayer. Since both the N-terminal and the C-terminal of this vesicle-bound protein are accessible to the externally added proteolytic enzymes, it is concluded that a loop of the polypeptide segment goes into the bilayer. These observations, taken together, suggest a possibility that the penetration by a loop of alpha-LA segment into the phospholipid bilayer is responsible for the fusion.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007768	Lactalbumin	A major protein fraction of milk obtained from the WHEY.	alpha-Lactalbumin,alpha-Lactalbumin A,alpha-Lactalbumin B,alpha-Lactalbumin C,alpha Lactalbumin,alpha Lactalbumin A,alpha Lactalbumin B,alpha Lactalbumin C
D008081	Liposomes	Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.	Niosomes,Transferosomes,Ultradeformable Liposomes,Liposomes, Ultra-deformable,Liposome,Liposome, Ultra-deformable,Liposome, Ultradeformable,Liposomes, Ultra deformable,Liposomes, Ultradeformable,Niosome,Transferosome,Ultra-deformable Liposome,Ultra-deformable Liposomes,Ultradeformable Liposome
D009113	Muramidase	A basic enzyme that is present in saliva, tears, egg white, and many animal fluids. It functions as an antibacterial agent. The enzyme catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrin. EC 3.2.1.17.	Lysozyme,Leftose,N-Acetylmuramide Glycanhydrolase,Glycanhydrolase, N-Acetylmuramide,N Acetylmuramide Glycanhydrolase
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D010714	Phosphatidylethanolamines	Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.	Cephalin,Cephalins,Ethanolamine Phosphoglyceride,Ethanolamine Phosphoglycerides,Ethanolamineglycerophospholipids,Phosphoglyceride, Ethanolamine,Phosphoglycerides, Ethanolamine
D010718	Phosphatidylserines	Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a SERINE moiety.	Serine Phosphoglycerides,Phosphatidyl Serine,Phosphatidyl Serines,Phosphatidylserine,Phosphoglycerides, Serine,Serine, Phosphatidyl,Serines, Phosphatidyl
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
D003574	Cytochrome c Group	A group of cytochromes with covalent thioether linkages between either or both of the vinyl side chains of protoheme and the protein. (Enzyme Nomenclature, 1992, p539)	Cytochromes Type c,Group, Cytochrome c,Type c, Cytochromes
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