Part:BBa_K2924030

ɑ-lactalbumin

ɑ-lactalbumin from Bos taurus

Usage and Biology

Introduction

In order to create SynMylk the focus was set on the production of the most abundant proteins which are usually divided into two categories: Those proteins that are very insoluble in water and occur in cheese, the caseins (ɑ-s1-, ɑ-s2-, β- and κ-casein), and those proteins that are normally filtered away during manufacturing of dairy products, which are called whey proteins (ɑ-lactalbumin, β-lactoglobulin)¹.

These proteins originate from Bos taurus, but since the isolation of the respective genes directly from the native organism is quite complex, they were synthesized commercially and optimized for the heterological expression in microbial hosts e.g. Escherichia coli, Bacillus subtilis and Synechocystis sp. PCC 6803. The gene sequences for the targeted milk proteins were generated by reverse translation of the amino acid sequence.

Whey Proteins

Whey proteins are described as a group of soluble milk proteins which are present in the liquid solution form after precipitation of the insoluble caseins¹. The main constituents are ɑ-lactalbumin and β-lactoglobulin. Both are of low molecular weight and therefore represent rather small proteins. They make up approximately 70-80% of the total whey protein content in native cow's milk. In the last few years whey proteins gained importance as a major component in nutritional industry because they promote a huge variety of health, biological and nutritional aspects².

ɑ-Lactalbumin

The second most significant protein in bovine milk, with 2-5% of total protein amount and with an concentration of 1-1.5 g/L is the ɑ-lactalbumin³. The corresponding gene coding for this small protein is located at chromosome 5⁴. ɑ-lactalbumin is able to bind cations, which facilitate the absorption of important minerals². Furthermore it has an important connection to lactose biosynthesis and significant biological functions⁵. Previously, it had been described that ɑ-lactalbumin and its hydrolysate have many physiological traits, such as stress reduction, antimicrobial activity, antihypertensive effects, regulation of cell growth and other beneficial effects on the health². Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BglII site found at 338
  Illegal BamHI site found at 427
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

References

1: Eel, W. N., et al. "Nomenclature of proteins of cow's milk: fifth revision." Journal of Dairy Science 67.8 (1984): 1599-1631.ig

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: Chatterton, Dereck EW, et al. "Bioactivity of β-lactoglobulin and α-lactalbumin—Technological implications for processing." International Dairy Journal 16.11 (2006): 1229-1240.

4: https://www.ncbi.nlm.nih.gov/gene/281894

5: Kronman, Martin J., S. K. Sinha, and K. Brew. "Characteristics of the binding of Ca2+ and other divalent metal ions to bovine alpha-lactalbumin." Journal of Biological Chemistry 256.16 (1981): 8582-8587.