Demonstration of proline-rich proteins in rabbit parotid saliva and partial characterization of some of the proteins

Critical Reviews in Oral Biology & Medicine

2002

384

265

Tannins are polyphenols that occur widespread in plant-based food. They are considered to be part of the plant defense system against environmental stressors. Tannins have a number of effects on animals, including growth-rate depression and inhibition of digestive enzymes. Tannins also have an effect on humans: They are, for example, the cause of byssinosis, a condition that is due to exposure to airborne tannin. Their biological effect is related to the great efficiency by which tannins precipitate proteins, an interaction that occurs by hydrophobic forces and hydrogen bonding. Two groups of salivary proteins, proline-rich proteins and histatins, are highly effective precipitators of tannin, and there is evidence that at least proline-rich proteins act as a first line of defense against tannins, perhaps by precipitating tannins in food and preventing their absorption from the alimentary canal. Proline plays an important role in the interaction of proline-rich proteins with tannins. In contrast, it is primarily basic residues that are responsible for the binding of histatins to tannin. The high concentration of tannin-binding proteins in human saliva may be related to the fruit and vegetable diet of human ancestors.

Section: (B) P Roline -Richproteinsmentioning

confidence: 99%

Interaction of Plant Polyphenols with Salivary Proteins

Critical Reviews in Oral Biology & Medicine

2002

384

265

“…Saliva from many species, including human, monkey, rat, mouse and rabbit, contains a family of so-called proline-rich proteins (PRPs) [6,[17][18][19][20]. Small amounts of PRPs are also present in human tracheobronchial secretions [21].…”

Section: Introductionmentioning

confidence: 99%

Identification of histatins as tannin-binding proteins in human saliva

Qin

1995

Biochemical Journal

123

Tannins have a number of detrimental biological effects and these include interference with normal growth and metabolism if they are present in the feed of various animals. Proline-rich proteins (PRPs) in saliva have been shown to provide protection against tannin, but little is known about the mechanism of protection and interaction of other salivary proteins with tannin. To identify tannin-binding human salivary proteins, parotid and submandibular/sublingual saliva samples were adsorbed with tannin. PRPs, and in particular a group of low-M(r) proteins, were readily precipitated by tannin. The low-M(r) proteins were purified from parotid saliva and demonstrated to be histatins, a family of well-characterized histidine-rich salivary proteins. The ability of synthetic histatin 5, as well as an acidic PRP (PRP-1) and gelatin to precipitate quebracho condensed tannin and tannic acid was determined. At pH 7.4 histatin 5 was the most effective precipitant of both condensed tannin and tannic acid and it also precipitated the largest amount of condensed tannin at pH 3.0, but the smallest amount of tannic acid at that pH. In contrast PRP-1 showed a greater ability to precipitate both condensed tannin and tannic acid at pH 3.0 than at pH 7.4. Under most circumstances histatin 5 was therefore more effective in precipitating tannins than proteins with high proline content which generally have been recognized as strong precipitants of tannin. Pre-incubation of tannic acid with alpha-amylase inhibited the enzyme, but addition of histatin 5 or the acidic PRP PIF-s protected amylase from inhibition by tannin. Similarly salivary proteins may protect other biological activities in the digestive tract from inhibition by dietary tannin.

“…Small amounts of these proteins are also present in the respiratory tract (Warner and Azen, 1984) and in the pancreas (Ito et al, 1983), indicating that their function is not restricted to some unusual aspect of the oral cavity. PRPs have also been demonstrated in the saliva or salivary glands of various animals including monkeys (Oppenheim et al, 1979), rats (Fernandez-Sorenson andCarlson, 1974), mice (Mehansho et al, 1985), hamsters (Mehansho et al, 1987), and rabbits (Rajan and Bennick, 1983).…”

Section: Introductionmentioning

confidence: 99%

Alignment of Amino Acid and DNA Sequences of Human Proline-rich Proteins

Kauffman

Keller

Critical Reviews in Oral Biology & Medicine

et al. 1993

Self Cite

Human proline-rich proteins (PRPs) constitute a complex family of salivary proteins that are encoded by a small number of genes. The primary gene product is cleaved by proteases, thereby giving rise to about 20 secreted proteins. To determine the genes for the secreted PRPs, therefore, it is necessary to obtain sequences of both the secreted proteins and the DNA encoding these proteins. We have sequenced most PRPs from one donor (D.K.) and aligned the protein sequences with available DNA sequences from unrelated individuals. Partial sequence data have now been obtained for an additional PRP from D.K. named II-1. This protein was purified from parotid saliva by gel filtration and ion-exchange chromatography. Peptides were obtained by cleavage with trypsin, clostripain, and N-bromosuccinimide, followed by column chromatography. The peptides were sequenced on a gas-phase protein sequenator. Overlapping peptide sequences were obtained for most of II-I and aligned with translated DNA sequences. The best fit was obtained with clones containing sequences for the allele PRB4M (Lyons et al., 1988). However, there was not complete identity of the protein amino acid sequence and the DNAderived sequences, indicating that II-I is not encoded by PRB4M. Other PRPs isolated from D.K. also fail to conform to any DNA structure so far reported. This shows the need to obtain amino acid sequences and corresponding DNA sequences from the same person to assign genes for the PRPs and to determine the location of the postribosomal cleavage points in the primary translation product.