Isolation and purification of beta-lactoglobulin from cow milk.

Ranjit Aich,Subhasis Batabyal,Siddhartha Narayan Joardar

doi:10.14202/vetworld.2015.621-624

Abstract

Aim:The present study was undertaken to standardize a convenient method for isolation and purification of β-lactoglobulin (β-lg) from cow milk keeping its antigenicity intact, so that the purified β-lg can be used for detection of cow milk protein intolerance (CMPI).Materials and Methods:Raw milk was collected from Gir breed of cattle reared in Haringhata Farm, West Bengal. Milk was then converted to skimmed milk by removing fat globules and casein protein was removed by acidification to pH 4.6 by adding 3 M HCl. β-lg was isolated by gel filtration chromatography using Sephacryl S-200 from the supernatant whey protein fraction. Further, β-lg was purified by anion-exchange chromatography in diethylaminoethyl-sepharose. Molecular weight of the purified cattle β-lg was determined by 15 percent one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was analyzed by gel documentation system using standard molecular weight marker.Results:The molecular weight of the purified cattle β-lg was detected as 17.44 kDa. The isolated β-lg was almost in pure form as the molecular weight of purified β-lg monomer is 18kDa.Conclusion:The study revealed a simple and suitable method for isolation of β-lg from whey protein in pure form which may be used for detection of CMPI.

Highlights

Milk whey contains a heterogeneous group of proteins that can be derived from blood or synthesized in the mammary gland
Milk was converted to skimmed milk by removing fat globules and casein protein was removed by acidification to pH 4.6 by adding 3 M HCl. β-lg was isolated by gel filtration chromatography using Sephacryl S-200 from the supernatant whey protein fraction
The study revealed a simple and suitable method for isolation of β-lg from whey protein in pure form which may be used for detection of cow milk protein intolerance (CMPI)

Summary

Introduction

Milk whey contains a heterogeneous group of proteins that can be derived from blood or synthesized in the mammary gland. Betalactoglobulin (β-lg), a major whey protein found in the milk of cows and other ruminants is considered as a milk allergen [1,2,3,4] It is not an endogenous substance in human, rodents, and lagomorph’s milk. Β-lg, a major protein that accounts for approximately 10-15% of total milk proteins and 58% of whey protein, exists at the normal pH of bovine milk as a dimer with a molecular weight of 36 kDa [5]. It is a single chain polypeptide of 18 kDa comprising of 162 amino acid residues. It could have a role in metabolism of phosphate in the mammary gland [7] and the transport of retinol and fatty acids in the gut [8], or in the transfer of passive immunity

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Conclusion