Genotyping, physicochemical characterization, and protein isoform quantification of β-casein A2 milk in chinese simmental and Angus cattle

  • Adhita Prabakusuma College of Food Science and Technology, Yunnan Agricultural University, Kunming, China – 650201
  • Hamzah Aleryani College of Food Science and Technology, Yunnan Agricultural University, Kunming, China – 650201

Abstract

The recent findings on β-casein (β-CN) A2 cattle’s milk variant have triggered global research interest, as it is claimed to be a safer
choice for human health. Only a few studies have been performed to investigate the presence of β-CN A1 and A2 alleles of the CSN2
gene in dual-purpose Simmental and Angus cattle in Yunnan province, China. This present study aimed to genotype cattle producing A2
milk, predict the physicochemical properties, and quantify the isoform concentration of β-CN A2 protein. Blood samples were collected
from 286 cattle (201 Simmental and 85 Angus breeds). Genotyping was performed using polymerase chain reaction-restriction fragment
length polymorphism (PCR-RFLP) coupled with the sequencing method. Physicochemical properties were predicted using several webbased bioinformatics tools. A sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure β-CN A2 protein isoform
concentration in fresh A2 milk. Allele frequencies of β-CN A2 were more dominant in Simmental (0.642) and Angus (0.835) than A1.
The β-CN A1A2 genotype was most frequent in Simmental (44.8%), while A2A2 genotype was primarily found in Angus (70.6%). The
predicted monoisotopic mass, molecular weight, isoelectric point (pI), net charge at pH 7, total number of atoms, instability index, and
grand average of hydropathicity (GRAVY) of β-CN A2 were 23,567.23 Da, 23,582.30 Da, 5.24, –6.5, 3,357, 96.53, and –0.355,
respectively. The β-CN A2 protein isoform concentration in Angus (17.8 ng/ml) was higher than in Simmental (16.7 ng/ml). Identifying
β-CN A2 milk provides new insights for screening favorable alleles and establishing breeding programs based on marker-assisted selection.

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How to Cite
Prabakusuma, A., and H. Aleryani. “Genotyping, Physicochemical Characterization, and Protein Isoform Quantification of β-Casein A2 Milk in Chinese Simmental and Angus Cattle”. Emirates Journal of Food and Agriculture, Vol. 34, no. 8, Aug. 2022, doi:https://doi.org/10.9755/ejfa.2022.v34.i8.2882. Accessed 8 Feb. 2023.
Section
Research Article