Use of urea-polyacrylamide electrophoresis for discrimination of A1 and A2 beta casein variants in raw cow’s milk
Beta-casein (BC) in cow’s milk occurs in several genetic variants, where BC A1 (BCA1) and BC A2 (BCA2) are the most frequent. This work deals with a method based on modified polyacrylamide gel electrophoresis using urea PAGE to discriminate BCA1 and BCA2 variants from Holstein Friesian (HF) and genetically selected Jersey A2/A2 (JA2) cow’s milk. Two well defined bands were obtained from BC fraction of HF milk, while that of JA2 showed a single band. Proteins from these bands were sequenced by HPLC-quadrupole linear ion trap/mass spectrometry, resulting in BCA1 and BCA2 separation from the BC fraction of HF milk, whereas BCA2 was the only constituent of JA2 fraction. This method represents a feasible and useful tool to on site phenotyping of BC fraction of cow’s milk for pharmaceutical and food industries applications.
KeywordsCow’s milk Beta casein A1 Beta casein A2 Polyacrylamide gel Mass spectrometry
Tanks are given to CONACyT-PEI, for Grant No. C003V-2013-01-199586. Authors acknowledge Ecológico Tierra Viva breeders for genotyping control data and provision of milk samples. Authors thank Dr. C. Ferreira-Batista and E. Meneses-Romero from IBT, UNAM, México for technical support in BC sequencing.
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