Related Experiment Video
Updated: Aug 13, 2026
Purification of the M. magneticum Strain AMB-1 Magnetosome Associated Protein MamAΔ41
Published on: March 25, 2010
Rapid and simple procedure for purifying PAS-4 glycoprotein from bovine milk fat globule membrane
Abstract:
The isolation and partial characterization of PAS-4 glycoprotein (78 kDa) from bovine milk fat globule membrane (MFGM) is described. PAS-4 was selectively extracted with Triton X-114 nonionic detergent and then fractionated on DEAE-Sepharose at pH 7.5. The PAS-4 fraction that was not bound on DEAE-Sepharose gave a single band by SDS-PAGE. The recovery of PAS-4 was 57.4% from MFGM. An amino acid analysis found a high percentage of nonpolar residues. Approximately 7.2% of carbohydrate from PAS-4 was composed of mannose, galactose (Gal), N-acetylglucosamine, N-acetylgalactosamine (GalNAc), and sialic acid, most of the Gal and GalNAc in PAS-4 being released after mild alkaline hydrolysis. This indicated that PAS-4 contained both N- and O-linked sugar chains in concordance with the results of lectin affinity. PAS-4 had apparent isoelectric points of 7.45, 7.41, and 7.32, but these were shifted to pI 7.47 by a neuraminidase treatment. The apparent molecular weight of PAS-4 after deglycosylation with N-glycanase was approximately 57,000 by SDS-PAGE.
Insights
Researchers isolated and characterized PAS-4 glycoprotein from bovine milk fat globule membrane (MFGM). This glycoprotein contains both N- and O-linked sugar chains, with a significant portion of nonpolar amino acids.
Area of Science:
- Biochemistry
- Glycobiology
- Food Science
Background:
- Bovine milk fat globule membrane (MFGM) is a complex biological structure.
- Understanding MFGM glycoproteins is crucial for dairy science and nutrition.
- PAS-4 glycoprotein's specific role and composition were previously uncharacterized.
Purpose of the Study:
- To isolate and partially characterize the PAS-4 glycoprotein from bovine MFGM.
- To determine the composition and linkage of its carbohydrate chains.
- To analyze its amino acid profile and physicochemical properties.
Main Methods:
- Selective extraction using Triton X-114 nonionic detergent.
- Fractionation via DEAE-Sepharose chromatography.
- Analysis using SDS-PAGE, amino acid analysis, and lectin affinity.
Main Results:
- PAS-4 glycoprotein (78 kDa) was successfully isolated with 57.4% recovery.
- Amino acid analysis revealed a high percentage of nonpolar residues.
- Glycosylation analysis indicated the presence of both N- and O-linked sugar chains, including mannose, galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid.
Conclusions:
- PAS-4 is a glycoprotein with a distinct composition of nonpolar amino acids and complex glycan structures.
- The presence of both N- and O-linked glycans suggests diverse functional roles.
- Further investigation into PAS-4's biological functions within MFGM is warranted.
