Proline rich protein

Proline-rich proteins (PRPs) are a class of intrinsically disordered proteins^[1] (IDPs) containing several repeats of a short proline-rich sequence.

Many tannin-consuming animals secrete a tannin-binding protein (mucin) in their saliva. Tannin-binding capacity of salivary mucin is directly related to its proline content. Advantages in using salivary proline-rich proteins (PRPs) to inactivate tannins are :

• PRPs inactivate tannins to a greater extent than do dietary proteins; this results in reduced fecal nitrogen losses,^[2]
• PRPs contain non specific nitrogen and nonessential amino acids; this makes them more convenient for an animal to exploit rather than using up valuable dietary protein.^[3]

Example of this class of protein is IB5, a human parotid salivary protein known to bind with polyphenols (binding responsible for the astringency mouth feel). Other examples include Proline-Rich 12, Proline-Rich Protein 30, and Proline-Rich Protein 21.

References

1. Canon, Francis; Paté, Franck; Meudec, Emmanuelle; Marlin, Thérèse; Cheynier, Véronique; Giuliani, Alexandre; Sarni-Manchado, Pascale (2009). "Characterization, stoichiometry, and stability of salivary protein–tannin complexes by ESI-MS and ESI-MS/MS". Analytical and Bioanalytical Chemistry. 395 (8): 2535–2545. doi:10.1007/s00216-009-3180-3. PMID 19838685. S2CID 34081138.
2. de Wijk, René A.; Prinz, Jon F. (2005). "The role of friction in perceived oral texture". Food Quality and Preference. 16 (2): 121–129. doi:10.1016/j.foodqual.2004.03.002.
3. "Tanins chemistry on www.users.muohio.edu" (PDF). Archived from the original (PDF) on 2013-08-26. Retrieved 2010-01-19.