A highly selective two-way purification method using liquid chromatography for isolating αS2-casein from goat milk of five different breeds

Mohsin AZ 1 , Sukor R 2 , Selamat J 3 , Meor Hussin AS 4 , Ismail IH 5 , Jambari NN 3 Show all authors , Jonet A 6

Affiliations 

  • 1 Laboratory of Food Safety and Food Integrity, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
  • 2 Laboratory of Food Safety and Food Integrity, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia. Electronic address: rashidah@upm.edu.my
  • 3 Laboratory of Food Safety and Food Integrity, Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia; Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
  • 4 Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
  • 5 Faculty of Medicine, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
  • 6 Department of Structural Biology and Biophysics, Malaysia Genome Institute, Kajang 43000, Selangor, Malaysia
J Chromatogr B Analyt Technol Biomed Life Sci, 2020 Dec 01;1160:122380.
PMID: 32971369 DOI: 10.1016/j.jchromb.2020.122380

Abstract

The main challenges in the purification of αS2-casein are due to the low quantity in milk and high homology with other casein subunits, i.e., αS1-casein, β-casein, and κ-casein. To overcome these challenges, the aim of this study was to develop a two-step purification to isolate native αS2-casein in goat milk from five different breeds; British Alpine, Jamnapari, Saanen, Shami, and Toggenburg. The first step of the purification was executed by anion-exchange chromatography under optimal elution conditions followed by size exclusion chromatography. Tryptic peptides from in-gel digestion of purified αS2-casein were sequenced and analyzed by LC-ESI-MS/MS. From 1.05 g of whole casein, the highest yield of αS2-casein (6.7 mg/mL) was obtained from Jamnapari and the lowest yield (2.2 mg/mL) was from Saanen. A single band of pure αS2-casein was observed on SDS-PAGE for all breeds. The αS2-casein showed coverage percentage of amino acid sequence from 76.68 to 92.83%. The two-step purification process developed herein was successfully applied for isolating native αS2-casein from goat milk with high purity, which will allow for future in vitro studies to be conducted on this protein.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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