Proline rich proteins
proline rich proteins
Proline-rich proteins (PRPs) is a class of intrinsically unstructured proteins (IUP) 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, 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.   An 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).