Functional changes in beta-lactoglobulin by conjugation with cationic saccharides.
Bovine beta-lactoglobulin (beta-LG) was conjugated to each of three cationic saccharides [glucosamine (GlcN), chitopentaose (CPO), and chitosan (CHS)] by means of a water-soluble carbodiimide or by the Maillard reaction in an effort to improve the functional properties of beta-LG. The molar ratios of beta-LG to the cationic saccharide in the beta-LG-GlcN, beta-LG-CPO, and beta-LG-CHS conjugates were 2:1, 2:5, and 2:1, respectively. Fluorescence studies indicated that the conformation around Trp had changed in each conjugate and that the surface of each of the conjugates was covered with a saccharide chain. Structural analysis using monoclonal antibodies indicated that the conformation around (15)Val-(29)Ile (beta-sheet region) in beta-LG-GlcN and beta-LG-CPO had changed but that in beta-LG-CHS was maintained, whereas the conformation around (125)Thr-(135)Lys (alpha-helix region) in the conjugates had changed. The emulsifying activity of beta-LG was improved by conjugation with CPO or CHS, and aggregation of beta-LG was suppressed by conjugation with CHS. Reduction of the antigenicity and immunogenicity of beta-LG was achieved by conjugation with CHS.
Hattori
M
M
Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Japan. makoto@cc.tuat.ac.jp
Numamoto
K
K
Kobayashi
K
K
Takahashi
K
K
D000818:Animals; D002417:Cattle; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D005944:Glucosamine / Q000737:chemistry*; D006001:Glycoconjugates / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D007782:Lactoglobulins / Q000737:chemistry* / Q000378:metabolism*; D015416:Maillard Reaction; D009844:Oligosaccharides / Q000737:chemistry; D017433:Protein Structure, Secondary
D006001:Glycoconjugates; D007782:Lactoglobulins; D009844:Oligosaccharides; D002686:Chitin; D048271:Chitosan; D005944:Glucosamine