isolation of genetic variants of - international milk...
TRANSCRIPT
Isolation of genetic variants of β-casein from bovine milk for structural and functional studies
Introduction
Beta-casein (ß-CN), and proteins in milk generally, are a common source of bioactive peptides, and a variation in bioactive activity among the genetic variants of ß-CN is of great interest. Several analytic methods are capable of isolating ß-CN from milk by the usage of the denaturant Urea or organic solvents. The isocyanic acid of urea can potentially react with proteins causing unwanted carbamylation. Carbamylation can lead to undesired side-effects in in-vitro studies, e.g. change in os-molality and viability. In light of using genetic variants of ß-CN in structural and functional studies, it is in our interest to remove Urea from the purification process of ß-CN.
Objective
To obtain relatively pure β-CN genetic variants from bovine milk homozygous for β-CN without the usage of urea in the purification process
Results
From a A2A2 genetic variant of β-CN
Andersen P2, Jensen HB1, Nielsen BM1, Poulsen NA1, Young JF1, Larsen LB1 1Department of Food Science, Science and Technology, Aarhus University 2Corresponding author, Pe
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AARHUS UNIVERSITY
Figure 2: 2-DGE image of the purified β-CN A2A2 vari-ant. The different sports were as-signed according to earlier work from the labora-tory. In the table the spot inten-sities measured by PDQuest™ (normalized to the total spots amount).
Figure 1 LC-ESI/MS result of the purified β-CN A2A2 variant. A: A214 B: MS result C: Deconvoluted mass 23977kDa
A B C
Methods
Milk
Incubation (dark 4°C)
Skimming
Ultra-centrifugation
Supernatant Pellet (kept at -20°C)
Acid precipitation
Vacuum centrifugation
Characterization
Conclusion
Cooling induces the release of β-CN into the serum phase.
A purity of 95.72 % was obtained for the β-CN A2A2 variant.
It is possible to obtain relatively pure β-CN genetic variants from bovine milk homozy-gous for β-CN without the usage of urea.
DEPARTMENT OF FOOD SCIENCE