Comparison of Inhibitory Activity on Calcium Phosphate Precipitation by Acidic Proline-Rich Proteins, Statherin, and Histatin-1

Abstract

This study quantitatively compares the inhibition of calcium phosphate (CaP) precipitation by the salivary acidic proline-rich proteins (PRPs) statherin and histatin-1. Saliva and CaCl2 in 125 mM imidazole buffer (pH 7.0) were incubated with potassium phosphate and a hydroxyapatite (HAP) suspension, for 30 min at 25 degrees C, then filtered through nitrocellulose. The calcium (Ca) concentration in the filtrate was measured by atomic absorption spectrophotometry, then deducted from that in the initial solution to determine the amount of CaP precipitation after 30 min. The values of the inhibitory activities on CaP precipitation relative to crude parotid saliva were 4.7, 4.9, 6.9, and 65.8 for histatin-1, large PRPs, small PRPs, and statherin, respectively.

Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue

“…Our seeded crystal growth experiment results are generally congruent with those of previous research, which used constant composition systems to examine some pellicle precursor proteins where several authors found a concentration‐dependent inhibition of HA growth . Furthermore, the casein concentrations used in this study are also in a similar range to the levels of human salivary PRP and statherin, of 0–80 and 16–147 μ g ml −1 , respectively .…”

“…We can then speculate that casein, when present at concentrations physiologically comparable with those of pellicle precursor proteins, exhibit inhibitory behaviour similar to that of PRPs. Our seeded crystal growth experiment results are generally congruent with those of previous research, which used constant composition systems to examine some pellicle precursor proteins where several authors found a concentration-dependent inhibition of HA growth (13,(32)(33)(34). Furthermore, the casein concentrations used in this study are also in a similar range to the levels of human salivary PRP and statherin, of 0-80 and 16-147 lg ml À1 , respectively (39).…”

“…Previous reports have measured calcium and phosphate concentrations and pH changes as indicators of HA growth in seeded crystal growth systems . This study measured the calcium concentration, but not the phosphate ion concentration, in the AS solutions.…”

“…As this work focused on elucidating the effects of different concentrations of casein, direct comparison with reconstituted saliva was not carried out at this time and is thus a limitation of the present study. Previous reports have measured calcium and phosphate concentrations and pH changes as indicators of HA growth in seeded crystal growth systems (32)(33)(34). This study measured the calcium concentration, but not the phosphate ion concentration, in the AS solutions.…”

Chemical alteration by tooth bleaching of human salivary proteins that infiltrated subsurface enamel lesions —Experimental study with bovine lesion model systems—

“…Most of these bound proteins, however, could be removed using an in-office bleaching agent. More than 40 different proteins and peptides are present in saliva 18) , with certain proteins such as statherin having strong affinity for hydroxyapatite (HA) and inhibiting the growth of apatite crystals [19][20][21][22][23][24] . The concentration of statherin, which has similar proline content as proline rich proteins (PRPs), is sufficient to maintain a stable supersaturated HA solution 25) .…”