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

Aliah Zannierah Mohsin; Rashidah Sukor; Jinap Selamat; Anis Shobirin Meor Hussin; Intan Hakimah Ismail; Nuzul Noorahya Jambari; Anuar Jonet

doi:10.1016/j.jchromb.2020.122380

A highly selective two-way purification method using liquid chromatography for isolating α_S2-casein from goat milk of five different breeds

J Chromatogr B Analyt Technol Biomed Life Sci. 2020 Dec 1:1160:122380. doi: 10.1016/j.jchromb.2020.122380. Epub 2020 Sep 11.

Authors

Aliah Zannierah Mohsin¹, Rashidah Sukor², Jinap Selamat³, Anis Shobirin Meor Hussin⁴, Intan Hakimah Ismail⁵, Nuzul Noorahya Jambari³, Anuar Jonet⁶

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.

PMID: 32971369
DOI: 10.1016/j.jchromb.2020.122380

Abstract

The main challenges in the purification of α_S2-casein are due to the low quantity in milk and high homology with other casein subunits, i.e., α_S1-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 α_S2-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 α_S2-casein were sequenced and analyzed by LC-ESI-MS/MS. From 1.05 g of whole casein, the highest yield of α_S2-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 α_S2-casein was observed on SDS-PAGE for all breeds. The α_S2-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 α_S2-casein from goat milk with high purity, which will allow for future in vitro studies to be conducted on this protein.

Keywords: Goat breed; Goat α(S2)-casein; Ion-exchange chromatography; LC-ESI-MS/MS; Protein identification; Size-exclusion chromatography.

MeSH terms

Animals
Caseins* / analysis
Caseins* / chemistry
Caseins* / classification
Caseins* / isolation & purification
Chromatography, Liquid / methods*
Goats / classification*
Goats / metabolism
Milk / chemistry*
Milk / classification
Spectrometry, Mass, Electrospray Ionization / methods
Tandem Mass Spectrometry / methods

Substances

Caseins