Biomedical subjects

E C Moreno

Publications and source records attributed to E C Moreno.

At least 37 records · Page 2Linked to original sources

PubMed1991

Comparative solubility study of human dental enamel, dentin, and hydroxyapatite.

The solubility properties of hydroxyapatite (HA) are compared with those of human dental enamel and dentin. The apatites used in this study were equilibrated with dilute phosphoric acid solutions in CO2-containing atmospheres. The experimental results are interpreted in terms of solubility models which consider the biological materials as either HA or carbonatoapatites. Both in the HA and the dental mineral systems, the results are consistent with the precipitation of another carbonate-containing apatitic phase during equilibration. However, although the chemical behavior of the HA systems is in very good agreement with predictions based on the solubility models, the results with the bioapatites are not; this inconsistency is more marked for dentin than for enamel but in both cases the results clearly indicate the inadequacy of assuming for these dental apatites the stoichiometry of HA. The models and the experimental results show that, in principle, it is possible to define the two dental minerals in terms of respective solubility product constants, if independent information is attained on the stoichiometry of these bioapatites.

Bicuspid↗

PubMed1991

Changes in acid-phosphate content in enamel mineral during porcine amelogenesis.

The present study was undertaken to investigate changes in the acid-phosphate content of porcine enamel mineral during its development and to assess separately the HPO4(2-) pools in labile and stable forms. Enamel samples at the secretory and maturing stages of amelogenesis were obtained from the permanent incisors of five- to six-month-old slaughtered piglets. Human enamel from erupted, extracted teeth, synthetic hydroxyapatite, and carbonatoapatite containing acid phosphate were included as references. The acid-phosphate content of each sample was determined chemically through its pyrolytic conversion to pyrophosphate. The assessment of HPO4(2-) in labile forms was made by analysis of samples preequilibrated with solutions containing 3 mmol/L phosphate at pH11 (to de-protonate the HPO4(2-) species on crystal surfaces). The analytical results of porcine enamel samples showed that: (a) the outermost secretory (youngest) enamel contained the highest HPO4(2-), corresponding to about 16% of the total phosphate; (b) the acid-phosphate content decreased gradually to 10% in the inner (older) secretory and to 6% in the maturing tissue; (c) a substantial part of the HPO4(2-) in developing enamel tissue (50-60% of the HPO4(2-) for the secretory enamel) was in labile forms; and (d) the pool of the labile HPO4(2-) decreased with the growth of enamel mineral. In parallel studies with mature human enamel, it was ascertained that the total acid phosphate was only about 3% of the total phosphate, much lower than in developing porcine enamel, and that the labile pool of HPO4(2-) was also small, corresponding to about 15% of the total acid phosphate determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Amelogenesis↗

PubMed1990

Properties of phosphorylated 32 kd nonamelogenin proteins isolated from porcine secretory enamel.

Enamel proteins were isolated from specific locations of permanent porcine incisors at various developmental stages, namely, the outer (young) and inner (old) secretory, and maturing (chalk-like in appearance) enamel. The selective adsorption of these matrix proteins onto hydroxyapatite (HA) crystals was investigated in the presence of dissociative agents. The results showed that the proteins with the highest adsorption affinity were present at the highest concentration in the vicinity of the ameloblasts, i.e., in the outer enamel layer; a substantial reduction of these proteins was observed in the older (inner) secretory enamel and in the tissue in the maturing stage. An interesting finding was that a group of proteins having molecular masses of 32 kd present only in the inner secretory enamel, adsorbed strongly onto the HA crystals and were potent inhibitors of HA crystal growth. This 32 kd group contains phosphorylated glycoproteins; they are rich in Pro, Glu, Gly, and Asp and the N-terminal sequence was LXQVPGRIPPGYGRPPTP-, having no resemblance to the reported sequences of amelogenins. It was also found that the 32 kd moieties remained only as trace constituents in the maturing enamel, suggesting that most of them were removed as soluble constituents in the tissue fluid or further degraded by enzymatic activity during the late secretory stage. The results obtained support the view that amelogenetic mineralization is regulated by the presence of various organic matter and, importantly, that their efficacy as inhibitors of mineralization may be modulated through their degradation.

Amelogenesis↗

PubMed1990

Changes in the nature and composition of enamel mineral during porcine amelogenesis.

The present study was undertaken to investigate changes in the crystalline structure and composition of procine enamel mineral during amelogenesis. Special attention was given to the carbonate location in the forming apatite crystal. Enamel samples were obtained from the outer (young) secretory, inner (old) secretory, maturation, and mature (hard) enamel of the permanent incisors of slaughtered piglets. The crystalline structure and composition of these enamel samples were studied using Fourier transform infrared spectroscopy, X-ray diffraction, and chemical analyses. The initial enamel mineral in the outer secretory enamel was rich in acid phosphate and carbonate. The carbonate was mainly substituted for phosphate groups in the apatite crystals of the early (outer) secretory enamel. Developmental advancement from the outer secretory to the inner secretory (as well as early maturation) stages brought about significant changes in crystal parameters, namely, shrinkage and expansion of the c and a unit cell dimensions, respectively, and the shift of a v3 PO4 band to higher wavenumbers in the FTIR spectrum. X-ray diffraction patterns indicated that mineralization during the tissue maturation was characterized by a gradual growth of enamel crystals parallel to the a-axis direction. A most prominent finding was that, with developmental advancement, a decrease in CO3 per unit mass of P (or Ca) in the tissue, and a concomitant increase in the CO3 occupying OH sites in the crystalline lattice became apparent.

Ameloblasts↗

PubMed1990

Effects of fluoride on matrix proteins and their properties in rat secretory enamel.

This publication concerns the selective adsorption of rat enamel proteins onto hydroxyapatite, their solubility in aqueous solutions, and the effect that systemic fluoride has on these properties. The enamel proteins used as adsorbates were extracted in 0.5 mol/L acetic acid from the secretory enamel of the upper and lower incisors of SD rats (females, 200-220 g body weight). Equilibration of the proteins with hydroxyapatite was performed in two solutions: (i) 50 mmol/L acetate buffer at pH 6.0 and 0 degrees C, and (ii) 50 mmol/L Tris buffer containing 4 mol/L guanidine at pH 7.4 and room temperature. Enamel was dissected from animals, which were given either de-ionized water (control group) or water containing 25, 50, 75, or 100 ppm fluoride as NaF for four weeks. From these enamel samples, the proteins were extracted in sequence with 160 mmol/L NaCl and 3 mmol/L phosphate (pH 7.3), 50 mmol/L carbonate buffer (pH 10.8), and finally, with 0.5 mol/L acetic acid for dissolution of the enamel mineral. The F, Ca, and P contents of the various enamel samples were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗

PubMed1990

Effect of solution composition on morphological and structural features of carbonated calcium apatites.

The composition of enamel mineral corresponds to that of a calcium carbonato-apatite. For insight to be gained into the precipitation of carbonato-apatites having specific properties (crystal size, morphology, and carbonate incorporation into the crystal lattice), apatites were prepared at 80 degrees C in aqueous systems having various CO3 concentrations and pH values of around 7.5 or 10.5 (+/- 0.5). The various preparations had a wide range (0.005 to 0.19) of CO3/Ca molar ratios that bracket the ratios found in porcine enamel mineral at various developmental stages. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction analyses showed that the calcium apatites precipitating at neutral pH incorporated the carbonate into both the hydroxyl and phosphate ion sites in their lattices (A,B-types), whereas the preparations made at the alkaline pH (high OH-(-)CO3(2-)-competition) or in the presence of fluoride (F-(-)CO3(2-) competition) yielded only the B-type carbonato-apatite. It was also ascertained that the size and morphology of the carbonato-apatites, assessed by specific surface area determination and high-resolution electron microscopy, were highly dependent on the driving force for precipitation and the presence of regulators (CO3(2-) and F-) in solution. In neutral media, early precipitates were thin-ribbon in appearance, but grew into crystals having flattened-hexagonal cross-sections. In the presence of fluoride or in alkaline media, acicular apatite crystals, precipitated initially, grew into large rod-like carbonato-apatites having a symmetric-hexagonal cross-section. In both neutral and alkaline solutions, carbonate inhibited the growth of apatite crystals along their c axis, leading to the formation of bulkier crystals. The formation of carbonato-apatites at the neutral pH and their properties are consistent with observations made on enamel minerals formed in the early developmental stages.

Apatites↗

PubMed1990

Physicochemical perspectives on the cariostatic mechanisms of systemic and topical fluorides.

The cariostatic mechanisms of systemic and topical fluoride agents are considered in light of a previously proposed model for the caries process. It is noted that fluoride, in principle, can induce a cariostatic effect: by (1) reducing enamel solubility when incorporated into the mineral structure; (2) by fostering the remineralization of incipient enamel lesions and the deposition of fluoridated phases (within dental plaque) which provide a source of mineral ions (Ca, P, F) under acidic conditions; and (3) by reducing the net rate of transport of matter out of the enamel surface, under acidic conditions, by inducing the reprecipitation of fluoridated hydroxyapatite phases within enamel. It is also noted that relatively high (approximately 12,000 ppm) concentrations of professionally applied topical fluorides significantly reduce the rate of acid production of cariogenic organisms (e.g., S. mutans). Based on an analysis of available clinical and laboratory data, it is concluded that the benefits provided by water fluoridation result, to a large degree, from a topical effect. It is suggested that clinical procedures be developed to establish and maintain low levels of free fluoride in plaque fluid. It appears that this will require frequent exposure to topical fluorides.

Cariostatic Agents↗

PubMed1990

Solubility of human enamel mineral.

The solubility of human enamel was investigated in dilute phosphoric acid solutions (0.07 mMols/L to 1.54 mMols/L) under controlled partial pressures of CO2 (0.005% to 3.33% in mixtures with N2) at 25 degrees C. The enamel mineral was considered as carbonatoapatite containing acid phosphate having the stoichiometry [Ca]5-x-y[HPO4]v[PO4]3-x[CO3]w[OH]l-x-y. During equilibration, a second apatitic phase precipitated, as observed under the electronmicroscope. Solubility models are advanced consistent with the adapted stoichiometry and the precipitation of the second phase. The latter appears to have a carbonate content similar to that of the enamel mineral even when precipitated under the lowest partial pressure of CO2, suggesting that a molar content of about 0.3 of carbonate stabilizes the apatitic lattice. Based on the adopted stoichiometry of enamel mineral, Ca4.34 (HPO4).08 (CO3).29 (PO4)2.63 (OH).05, its solubility product constant was calculated as Ksp = 1.74 (+/- 0.081)x10(-6), expressed as the mean activity product.

Calcium↗

PubMed1990

Molecular conformation of porcine amelogenins and its significance in protein-mineral interaction: 1H-NMR photo-CIDNP study.

The present 1H-nmr study was undertaken to investigate the molecular structure of porcine amelogenins in solution using photo-CIDNP (chemically induced dynamic nuclear polarization). The proteins of interest were the parent 25 kD amelogenin consisting of 173 amino acid residues and its degraded products having molecular masses of 23 kD, 20 kD, 13 kD and 5 kD on SDS-PAGE. From the recorded 1H-nmr and photo-CIDNP spectra, it was found that: 1) the Trp161 at the C-terminus of the 25 kD protein showed a stronger photo-CIDNP effect than the other two Trp25,45 at the N-terminus; 2) Tyr residues at the N-terminus of the 25 kD and 20 kD amelogenins gave rise to the strong peak around 6.8 ppm, indicating that at least some of the six Tyr residues are surface residues; and 3) the accessibility of His residues was quite different between the 13 kD fragment and the 25 kD and 20 kD proteins. These results suggest that the hydrophilic segment at the C-terminus is most likely exposed on the molecular surface and that the molecular structure of the amelogenin in solution may change substantially by the cleavage of the segments at the N- and C-termini.

Amelogenin↗

PubMed1989

Possible function of matrix proteins in fluoride incorporation into enamel mineral during porcine amelogenesis.

The present study was undertaken to elucidate the mechanism of fluoride incorporation into secretory enamel mineral, with porcine enamel used as a model. Although the fluoride content in the enamel varied greatly among the animals, we observed that the fluoride-to-calcium ratio in the enamel tissue was maximal at the beginning of the secretory stage; the F/Ca ratio decreased (and leveled off) with the advancement of mineralization. In vitro work showed that some of the fluoride in the secretory enamel tissue was removed with the extraction of organic matter, mostly amelogenins. Furthermore, coating hydroxyapatite crystals with enamel matrix proteins resulted in a retardation of fluoride incorporation into the crystals when exposed to fluoride solutions, as a result of an inhibition of apatite reprecipitation. We also confirmed that the growth kinetics of fluoridated apatite onto HA seeds decreased with increasing coverage of the seed surface with the enamel proteins. All the results of the present study strongly suggest that the fluoride incorporation into enamel mineral during the secretory stage may be regulated by the kinetics of mineralization, which is highly dependent on the driving force for precipitation and the presence of proteinaceous inhibitors, mainly amelogenins.

Amelogenesis↗

PubMed1989

Possible roles of partial sequences at N- and C-termini of amelogenin in protein-enamel mineral interaction.

The purpose of this study was to assess the functional significance of homologous sequences of mammalian amelogenins at their N- and C-termini. A porcine 5-kDa fragment corresponding to the N-terminal 45 residues of amelogenins was purified from the secretory enamel. The decapeptide TDKTKREEVD corresponding to the C-terminal 10 residues of amelogenins was synthesized according to conventional solid-phase procedures. The inhibitory activity of both moieties on apatite crystal growth was determined in a supersaturated solution having an ionic composition similar to that of the fluid phase separated from porcine secretory enamel. The 5-kDa amelogenin fragment was sparingly soluble in neutral solutions and (in condensed forms because of aggregation) showed no significant inhibition of crystal growth, whereas the fragment molecules pre-adsorbed onto the seed crystals yielded modest inhibition of hydroxyapatite precipitation. However, their inhibitory activity was significantly lower than that of parent porcine amelogenin (25-kDa molecular mass). The high solubility of synthesized decapeptide allowed us to determine the adsorption isotherm onto hydroxyapatite at 37 degrees C, at an ionic strength similar to that of the enamel fluid. The obtained adsorption isotherm was described by a Langmuir model; the adsorption affinity and the maximum adsorption sites were 6.2 mL/mumol and 0.53 mumol/m2, respectively. As expected from the low adsorption affinity, the peptide showed a much weaker inhibition of apatite crystal growth than the parent amelogenin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗

PubMed1988

Effect of fluoride in the apatitic lattice on adsorption of enamel proteins onto calcium apatites.

The selective adsorption of enamel proteins onto crystalline calcium apatites having different specific surface areas and various degrees of fluoride substitution was investigated. The proteins were obtained from the outer (close to the ameloblast) layer of secretory enamel of porcine permanent incisors. The adsorption of the enamel proteins was not affected markedly by the variation of specific surface area of the hydroxyapatites used as adsorbents, but it was enhanced substantially with increasing fluoride content in the crystalline lattice. Through the use of SDS- and two-dimensional polyacrylamide gel electrophoresis, it was shown that the originally secreted amelogenin (25 kd) as well as 60-90-kd and 5-6-kd molecules adsorbed most selectively onto the hydroxyapatites and that additional moieties having 21-23-kd and 14-18-kd molecular masses commenced to adsorb onto the apatitic surfaces with increasing degrees of fluoride substitution in the lattice. In contrast, the 20-kd amelogenin, a product partially degraded from the 25-kd amelogenin, showed no significant adsorption, even onto the fluoridated apatites. These results suggest that the retention of proteinaceous matrix in the developing enamel might be affected by the nature of the forming crystals.

Adsorption↗

PubMed1988

Composition of human plaque fluid.

The composition of pooled resting plaque fluid was determined in four groups of college-age students (18-22 years), each composed of 50 individuals, who abstained from oral hygiene for 36 hours and did not eat or drink for at least one hour prior to plaque collection. Plaque samples from each group were pooled under mineral oil in small centrifuge tubes and centrifuged at 37,000 g for one hour at 4 degrees C. Supernatants were then combined under mineral oil and centrifuged at 5000 g (4 degrees C) for 15 minutes. In general, the inorganic composition of plaque fluid in the four groups was quite similar and in agreement with values reported by other investigators, but quite different from those of saliva or serum. The mean composition was: Ca, 7.07 +/- 0.51 mmol/L; P, 23.2 +/- 5.3 mmol/L; Na, 18.6 +/- 2 mmol/L; K, 85.1 +/- 5.3 mmol/L; Mg, 3.9 mmol/L; Cl, 42.8 +/- 9 mmol/L; F, approximately 0.004 mmol/L; pH, 5.69 (5.63-6.01). Acetate, propionate, succinate, butyrate, lactate, and formate were determined in two samples analyzed, with acetate and propionate being the predominant acids found. It was also demonstrated, through the titration of one of the plaque fluid samples, that the observed buffer capacity in plaque fluid was mostly related to its organic acid composition. It was noted, however, that when the initial pH in plaque fluid exceeded 6.5, phosphate contributed significantly to the buffer capacity. The contribution of other soluble species (proteins, peptides, amino acids) to the observed buffering in plaque fluid appeared to be small.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

Composition of pooled resting plaque fluid from caries-free and caries-susceptible individuals.

The composition of pooled resting plaque fluid from 10 population samples, grouped according to age (8-11, 14-17, 18-25 years) and caries status (caries-free, CF, DMFS = 0; caries-susceptible, CS, DMFS greater than 10), was determined by means of ion chromatography. Subjects received a dental prophylaxis one week prior to plaque collection, abstained from oral hygiene for 48 hours, and did not eat or drink for at least one hour prior to plaque collection. Plaque samples from each group were pooled under mineral oil and centrifuged (15,000 g) for 45 minutes at ambient temperature. Supernatants were analyzed for organic acids, inorganic anions, mono- and divalent cations, and pH value. The ions Na+, NH4+, K+, Ca2+, Mg2+, Cl-, and phosphate were present in all samples. Acetic and propionic acids were predominant, comprising over 75% of the acid (anions) present under resting conditions. Succinic, lactic, formic, and butyric acids were present in lower concentrations. Within each age group, the mean values for pH and NH4+ concentration were higher in the caries-free group; the differences between mean values (CF: pH, 6.35; NH4+, 52 mmol/L; CS: pH, 5.85; NH4+, 37 mmol/L) were found to be statistically significant (p less than 0.05) when all data for the CF and CS groups were combined. Significantly higher concentrations of Mg2+ and butyric acid were also found for the combined CF data. Concentrations of all other constituents were similar. Calculations indicate that plaque fluid is supersaturated with respect to enamel mineral and dicalcium phosphate dihydrate, with a significantly higher degree of saturation with respect to enamel mineral in the CF group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

Composition and buffer capacity of pooled starved plaque fluid from caries-free and caries-susceptible individuals.

The composition of pooled starved plaque fluid from six population samples, grouped according to age (8-11, 12-16, 8-17, 18-22 years) and caries status (caries-free, CF, DMFS = 0; caries-susceptible, CS, DMFS greater than 10), was determined by means of ion chromatography. Prior to plaque collection, all subjects abstained from oral hygiene for 48 hours and fasted overnight. In addition, selected subjects also received a dental prophylaxis one week prior to plaque collection. Plaque samples from each group were pooled under mineral oil and centrifuged at 15,000 g (ambient temperature) for 45 minutes. Supernatants were then analyzed for organic acids, inorganic anions, and mono- and divalent cations. Plaque fluid samples from CF and from the CS subgroups were also titrated with standard HCl for exploration of the inherent buffer capacity. The ions Na+ NH4+, K+, Ca2+, Mg2+, Cl-, phosphate, and carbonate were present in all samples analyzed. Formic, acetic, propionic, butyric, and trace amounts of isobutyric and isovaleric acids were detected, with acetic and propionic acids comprising between 85 and 94% of the total acids. Little (less than 1 mmol/L) to no succinic or lactic acid was detected in starved plaque fluid. No apparent difference was detected in the composition and saturation status of pooled starved plaque fluid from CF and CS individuals. These results suggest that caries susceptibility is not necessarily correlated with the plaque fluid composition of pooled starved plaque. In addition, no apparent difference in the inherent buffer capacities of these samples could be detected, consistent with the noted similarities in composition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1987

Selective adsorption of porcine-amelogenins onto hydroxyapatite and their inhibitory activity on hydroxyapatite growth in supersaturated solutions.

The selective adsorption of amelogenins onto synthetic hydroxyapatite (HA) and their inhibitory activity on the seeded HA crystal growth were investigated using enamel proteins obtained from the outer layer of immature porcine-enamel (soft, cheeselike in consistency) of developing permanent incisors. Special interests were paid to the effect of a postsecretory degradation of the original amelogenin(s) on their adsorption and inhibitory activity. In the adsorption studies, it was apparent that the originally secreted amelogenin (25 K), proline, and histidine-rich protein (2a), as well as the higher molecular weight components (60-90 K), showed a strong adsorption affinity onto the HA. This adsorption of protein 2a was related to its inhibition of the crystal growth of seeded HA in a dilute supersaturated solution. On the other hand, the partially degraded product (20 K) of amelogenins, protein 2b, lost the high adsorption affinity onto the HA, and consequently showed no significant inhibitory activity. The observed selective adsorption of protein 2a onto HA was apparent at pH 6.0 and pH 7.4 even in the presence of dissociative solvents, such as 3 M urea or 2 and 4 M guanidine-HCl; however, this selective behavior was sensitive to changes in pH, and was not displayed at pH values of 7.8 or 10.8. The results suggest that the originally secreted amelogenin 2a may play an active role in amelogenesis, and that enamel mineralization could be regulated by the secretion of amelogenins and their inactivation through partial enzymic degradation, prior to their complete removal.

Adsorption↗

PubMed1987

The enamel fluid in the early secretory stage of porcine amelogenesis: chemical composition and saturation with respect to enamel mineral.

The present study reports on the separation of fluid from soft, "cheeselike" enamel of porcine permanent teeth in the secretory stage, and the determination of its chemical composition. The enamel tissues were dissected from mandibles of 5 to 6-month-old piglets and pooled under mineral oil in centrifuge tubes, and then centrifuged at 1.9-2.4 X 10(5) g for 1-1.5 hours. The yields of the fluid were 44.8 +/- 2.3 (mean +/- standard error) microliter/g of enamel tissue at 1.9 X 10(5) g, and 53.9 +/- 1.9 microliter/g at 2.4 X 10(5) g. A significant finding was that the total Ca concentration of the enamel fluid (3.9-6.0 X 10(-4) M) was lower than that of porcine serum (2.9 X 10(-3) M), reflecting a distinct, compartmentalized microenvironment, isolated from the circulating blood. Another significant finding was that the ionic calcium activity (5.3 X 10(-5) M) in the enamel fluid was one order of magnitude lower than the total Ca concentration. The averaged results of other determinations were: pH, 7.26; total [P], 3.9 mM; [Mg2+], 0.8 mM; [Na+], 140 mM; [K+], 20 mM; [Cl-], 150 mM; [F-], 5 X 10(-3) mM; and osmolality of the fluid, 312 mosmol/kg H2O (in the same range as that of the serum, 310 mosmol/kg H2O). The apparent electrical unbalance of the analytical data, 8.65 meq excess of positive charges, was ascribed to the presence of HCO3- in the fluid; the computed ionic strength was 164 mM.(ABSTRACT TRUNCATED AT 250 WORDS)

Amelogenesis↗

PubMed1987

Inhibition of calcium phosphate precipitation by human salivary acidic proline-rich proteins: structure-activity relationships.

Absence of precipitation of calcium phosphate salts onto tooth surfaces from human saliva, which is supersaturated with respect to calcium phosphate salts, has been attributed in part to the presence in the salivary secretions of a group of acidic proline-rich phosphoproteins (PRP). These macromolecules are considered to act by adsorbing onto dental enamel where they inhibit surface-induced precipitation of calcium phosphate salts. The inhibitory activity is known to be associated primarily with the amino-terminal region of the PRP. The aim of this study was to determine the features of the primary structure of this molecular segment responsible for inhibitory activity. The 30-residue, amino-terminal segment of PRP-3, which contains the two phosphoserines and 11 of the 13 carboxyl groups present in PRP-3, was obtained by tryptic digestion. This peptide, designated PRP-3(TI), was treated with thermolysin to give the monophosphopeptides, Val-PSer-Gln-Glu-Asp-Val-Pro and Leu-Val-Ile-Ser-Asp-Gly-Gly-Asp-PSer-Glu-Gln, and with alkaline phosphatase to give the dephosphorylated analog, PRP-3(TI)DP. The inhibitory activities of PRP-3(TI) and the derived peptides, a synthetic peptide, phosphoseryl-phosphoserine (PSer-PSer), and O-phosphoserine (PSer), were determined using an assay based on inhibition of seeded precipitation of calcium phosphate. Inhibitory activities, expressed as concentrations of inhibitors required to give standard inhibitory activities, were PRP-3(TI), 0.59 microM; PSer-PSer, 3.5 microM; the two monophosphopeptides, 29 and 32.5 microM; PRP-3(TI)DP, 56 microM; PSer, 329 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Phosphates↗