Biomaterial Database

Heat-induced interactions between the proteins of milk fat globule membrane and skim milk. 1995

H H Kim, and R Jimenez-Flores

Department of Food Science, University of Illinois, Urbana 61801, USA.

Milk fat globule membrane proteins in washed cream were analyzed using preparative isoelectric focusing followed by SDS-PAGE. Five major protein bands of milk fat globule membrane were observed with apparent molecular mass of 150, 67, 62.5, 51, and 49 kDa. The protein of band 5 (49 kDa) was well separated from the protein of band 4 (51 kDa). Heat-induced effects (72 and 87 degrees C for 2.5, 5, 10, 20, 30, and 60 min) on whole milk proteins were also investigated under nonreducing and reducing conditions to study disulfide interactions between serum proteins and those in the fat membrane. beta-Lactoglobulin and other milk serum proteins interacted readily with milk fat globule membrane and membrane proteins at 87 degrees C, but only slightly at 72 degrees C. However, the interactions between serum proteins and fat globule membrane proteins cannot be explained solely by disulfide linkage formation. Some membrane proteins, especially the 49-kDa protein (band 5), underwent drastic changes after heat treatment. Further characterization of the 49-kDa protein demonstrated that it binds concanavalin A; AA composition and N-terminal sequence of the protein were determined and compared with those reported in the literature.

UI	MeSH Term	Description	Entries
D007525	Isoelectric Focusing	Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point.	Electrofocusing,Focusing, Isoelectric
D007526	Isoelectric Point	The pH in solutions of proteins and related compounds at which the dipolar ions are at a maximum.	Isoelectric Points,Point, Isoelectric,Points, Isoelectric
D008055	Lipids	A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)	Lipid
D008562	Membrane Glycoproteins	Glycoproteins found on the membrane or surface of cells.	Cell Surface Glycoproteins,Surface Glycoproteins,Cell Surface Glycoprotein,Membrane Glycoprotein,Surface Glycoprotein,Glycoprotein, Cell Surface,Glycoprotein, Membrane,Glycoprotein, Surface,Glycoproteins, Cell Surface,Glycoproteins, Membrane,Glycoproteins, Surface,Surface Glycoprotein, Cell,Surface Glycoproteins, Cell
D008892	Milk	The off-white liquid secreted by the mammary glands of humans and other mammals. It contains proteins, sugar, lipids, vitamins, and minerals.	Cow Milk,Cow's Milk,Milk, Cow,Milk, Cow's
D008894	Milk Proteins	The major protein constituents of milk are CASEINS and whey proteins such as LACTALBUMIN and LACTOGLOBULINS. IMMUNOGLOBULINS occur in high concentrations in COLOSTRUM and in relatively lower concentrations in milk. (Singleton and Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed, p554)	Milk Protein,Protein, Milk,Proteins, Milk
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
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009077	Mucins	High molecular weight mucoproteins that protect the surface of EPITHELIAL CELLS by providing a barrier to particulate matter and microorganisms. Membrane-anchored mucins may have additional roles concerned with protein interactions at the cell surface.	Mucin
D004220	Disulfides	Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.	Disulfide