Purification and characterization of novel whey glycoprotein WGP-88 which binds to a monoclonal antibody to PAS-4 glycoprotein in the bovine milk fat globule membrane.
A monoclonal antibody to the PAS-4 glycoprotein (78 kDa) of the bovine milk fat globule membrane (MFGM) specifically recognized PAS-4, and was named KAS4. A component recognized by KAS4 was found in whey protein, this being a glycoprotein of 88 kDa by SDS-PAGE and named WGP-88. WGP-88 was purified and characterized in comparison with PAS-4. WGP-88 had apparent pI values of 6.45 and 6.39, while those of PAS-4 were 7.39 and 7.35. Neuraminidase digestion shifted the pI values of WGP-88 to 6.57 and of PAS-4 to 7.52. WGP-88 was rich in polar amino residues (44.9 mol%), while PAS-4 was abundant in nonpolar amino acid residues (48.7 mol%). WGP-88 contained 17.1% of carbohydrate and PAS-4 had 7.2%. The results of reductive hydrolysis, N-glycanase digestion, and a lectin blot analysis suggested that N- and O-linked sugar chains were contained in both glycoproteins. WGP-88 and PAS-4 had a different N-terminal amino acid sequence. WGP-88 and PAS-4 respectively inhibited competitively the binding of KAS4 to PAS-4 and WGP-88. Our studies revealed WGP-88 recognized by KAS4 mAb to be a novel whey protein and to have different biochemical properties from those of PAS-4.
Hwangbo
S
S
Department of Applied Biochemistry, College of Agriculture, Utsunomiya University, Japan.
Azuma
N
N
Kurisaki
J
J
Kanno
C
C
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism*; D001201:Ascites / Q000378:metabolism; D001667:Binding, Competitive; D002241:Carbohydrates / Q000032:analysis; D002417:Cattle; D037102:Lectins / Q000032:analysis; D008055:Lipids / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000276:immunology*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000302:isolation & purification*; D008970:Molecular Weight; D010449:Peptide Mapping; D011485:Protein Binding
D000911:Antibodies, Monoclonal; D002241:Carbohydrates; D037102:Lectins; D008055:Lipids; D008562:Membrane Glycoproteins; D008894:Milk Proteins