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β-lactoglobulin

β-lactoglobulin from Bos taurus

Usage and Biology

Introduction

To creating SynMylk we will focus on the most abundant proteins which are usually divided into two categories: Those proteins that are very insoluble and occur in cheese, the caseins (ɑ-s1-, ɑ-s2-, β- and κ-casein), and those proteins that get filtered out during cheese making, which are called whey proteins (ɑ-lactalbumin, β-lactoglobulin)¹.

Those proteins originate from Bos taurus, but since the isolation of these genes directly from the native organism is quite complex they were synthesized commercially and optimized for the heterological expression in our chassis Escherichia coli and Bacillus subtilis. The gene sequences for the milk proteins were obtained by reverse translation of the protein sequence. They were ordered for codon-optimized syntheses for E. coli.

Whey Proteins

Whey proteins describe the group of milk proteins which are present in liquid form as whey after precipitation of caseins¹. The main components are ɑ-lactalbumin and β-lactoglobulin, both are small milk proteins and make up approximately 70-80% of the total whey protein. They are involved in a variety of health, biological and nutritional aspects².

ɑ-Lactalbumin

The most essential whey protein of bovine animals is β-lactoglobulin with a concentration of 3.2 g/L and it accounts about 10% of the total protein in bovine milk³. The monomer β-lactoglobulin is located on chromosome 6 ^4,5. β-lactoglobulin has an influence on the adhesion of hydrophobic substances such as fatty acids and their transport⁶. In addition, β-lactoglobulin not only provides the composition of milk, but also has positive health aspects, by binding retinol, and therefore promoting the absorption of vitamin A from milk^7,8.

Sequence and Features

References

1: Eigel, W. N., Butler, J. E., Ernstrom, C. A., Farrell Jr, H. M., Harwalkar, V. R., Jenness, R., & Whitney, R. M. (1984). Nomenclature of proteins of cow's milk: fifth revision. Journal of Dairy Science, 67(8), 1599-1631.

2: Stanciuc, Nicoleta, and Gabriela Rapeanu. "An overview of bovine [alpha]-lactalbumin structure and functionality." The Annals of the University of Dunarea de Jos of Galati. Fascicle VI. Food Technology 34.2 (2010): 82.

3: Le Maux, S., Bouhallab, S., Giblin, L., Brodkorb, A., & Croguennec, T. (2014). Bovine β-lactoglobulin/fatty acid complexes: binding, structural, and biological properties. Dairy science & technology, 94(5), 409-426.

4: Kontopidis, G., C. Holt, and L. Sawyer. "Invited review: β-lactoglobulin: binding properties, structure, and function." Journal of dairy science 87.4 (2004): 785-796.

5: Mercier, Jean-Claude, and Jean-Luc Vilotte. "Structure and function of milk protein genes." Journal of dairy science 76.10 (1993): 3079-3098.

6: Pérez, Maria Dolores, and Miguel Calvo. "Interaction of β-lactoglobulin with retinol and fatty acids and its role as a possible biological function for this protein: a review." Journal of dairy science 78.5 (1995): 978-988. 7: Tsutsumi, Rie, and Yasuo M. Tsutsumi. "Peptides and proteins in whey and their benefits for human health." Austin J Nutri Food Sci 1.1 (2014): 1002. 8: Papiz, M. Z., et al. "The structure of β-lactoglobulin and its similarity to plasma retinol-binding protein." Nature 324.6095 (1986): 383.