Phosvitin Explained

Phosvitin is one of the egg (commonly hen's egg) yolk^{[1] [2]} phosphoproteins known for being the most phosphorylated protein found in nature.^{[3] [4] [5]} Phosvitin isolation was first described by Mecham and Olcott in the year 1949.^{[3] [6]} Recently it has been shown that phosvitin orchestrates nucleation and growth of biomimetic bone like apatite.^[7]

Structure

As the most phosphorylated natural protein, phosvitin contains 123 phosphoserine residues accounting for 56.7% of its total 217 amino acid residues.^[8] The structure of phosvitin at large consists of 4-12 base pair stretches of serines, interspersed with amino acid residues lysine (6.9%), histidine (6.0%), and arginine (5.1%), among others in smaller quantities. Phosvitin’s structure (right) is adapted from the protein vitellogenin (Gene: VTG2; Uniprot: P02845; residues 1-1850) generated by AlphaFold, where all the possible phosphorylated serine residues are highlighted in red. Phosvitin is one of four proteins cleaved from vitellogenin and is unstructured at neutral pH. Despite phosvitin only accounting for 16% of total proteins in egg yolk, it alone accounts for 60% of the total yolk phosphoproteins as well as 90% of the total yolk phosphorus.^[9]

Function

Due to phosvitin’s polyanionic activity, the protein performs functionalities such as metal chelation, emulsification, and nutrition sequestration for a growing embryo. Additionally, in recent research it has been shown that the disordered secondary structure of phosvitin orchestrates nucleation and growth of biomimetic bone like apatite.

Further reading

• Egg yolk protein and egg yolk phosvitin inhibit calcium, magnesium, and iron absorptions in rats.. Ishikawa. SI. Journal of Food Science. Aug 2007. 72. 6. S412–S419. etal. 10.1111/j.1750-3841.2007.00417.x. 17995699.
• Mecham . Dale K. . Olcott . Harold S. . 1949 . Phosvitin, the principal phosphoprotein of egg yolk . Journal of the American Chemical Society . 71 . 11. 3670–3679 . 10.1021/ja01179a028.
• A simple and efficient method for preparing partially purified phosvitin from egg yolk using ethanol and salts. K. Y.. Ko. 10.3382/ps.2010-01138. 21489960. Poultry Science. 90. 5. 1096–1104. etal. 2011. free.
• Book: Huopalahti, Rainer. Bioactive Egg Compounds. Springer. etal.
• Book: Phosvitin. Marc . Anton. Oscar. Castellani. Catherine . Guérin-Dubiard. 17–24. 10.1007/978-3-540-37885-3_4. Springer Berlin Heidelberg. 9783540378839. 2007.

Notes and References

1. Preparation And Characterization Of Phosvitin From Hen Egg Yolk. F. J.. Joubert. W. H.. Cook. 10.1139/o58-045. 13511246. Canadian Journal of Biochemistry and Physiology. 1958. 36. 4. 399–408.
2. Relative and total abundance of constituent phosphoproteins from hen phosvitin in egg yolk . Richard C.. Clark. International Journal of Biochemistry. 12. 4. 1980. 651–653. 10.1016/0020-711x(80)90021-x. 7428998.
3. Egg Yolk Phosvitin and Functional Phosphopeptides—Review. Himali . Samaraweera. Journal of Food Science. 76. 7. R143–R150. Sep 2011. 10.1111/j.1750-3841.2011.02291.x. 21806612.
4. Interaction Between Phosvitin and Iron and Its Effect on a Rearrangement of Phosvitin Structure. George. Taborsky. Biochemistry. 1963. 2. 2. 266–271. 10.1021/bi00902a010. 13980103.
5. The functional property of egg yolk phosvitin as a melanogenesis inhibitor. Samooel . Jung. Food Chemistry. 135. 3. Dec 2012. 993–998. etal. 10.1016/j.foodchem.2012.05.113. 22953815.
6. Chemical Characterization of the Phosphoprotein Phosvitin. The Journal of Biological Chemistry. 240. 10. Oct 1965. Samuel E.. Allerton. Gertrude E.. Perlmank. 3892–3898. 10.1016/S0021-9258(18)97126-7. free. 5891575.
7. Sarem. Melika. Lüdeke. Steffen. Thomann. Ralf. Salavei. Pavel. Zou. Zhaoyong. Habraken. Wouter. Masic. Admir. Shastri. V. Prasad. 2017-07-17. Disordered Conformation with Low Pii Helix in Phosphoproteins Orchestrates Biomimetic Apatite Formation. Advanced Materials . 29. 35. 1701629. 10.1002/adma.201701629. 28714191. 2017AdM....2901629S . 0935-9648.
8. Chang . Chang . Lahti . Todd . Tanaka . Takuji . Nickerson . Michael T . 2018-03-23 . Egg proteins: fractionation, bioactive peptides and allergenicity . Journal of the Science of Food and Agriculture . en . 98 . 15 . 5547–5558 . 10.1002/jsfa.9150 . 29797412 . 2018JSFA...98.5547C . 0022-5142.
9. Yilmaz . Birsen . Ağagündüz . Duygu . 2020-09-23 . Bioactivities of hen's egg yolk phosvitin and its functional phosphopeptides in food industry and health . Journal of Food Science . en . 85 . 10 . 2969–2976 . 10.1111/1750-3841.15447 . 32966601 . 0022-1147.