AU593365C - Phosphopeptides - Google Patents

Description

TITLE: PHOSPHOPEPTIOES This invention relates to phosphopeptide. and composi ions containing same. This invention also relates to caries and gingivitis inhibition. The present invention provides a phos ho eptide or a salt thereof, the phospho e i e having from 5 to 30 amino acids including the sequence A-B-C-D-E inhere A,8,C,D and E are inde endentl phosphoserine, phosphothreonine, phosphotyrosine, phosphohistidine, glutamate and aspartate. Preferred ph o s ph o e p t i de s are those wherein A,B and C are independently phosphoserine, phosphothreonine, phosphoty osine and phosphohis idine and 0 and E are independently phosphose ine, phosphothreonine, glutamate and aspartate. Particularly preferred phosphopeptides are those where A,B and C are phosphoserine and 0 and E are glutamate. The phospeptide is preferably in substan iall pure form. The phosphopeptides of the present invention or their salts may have utility in the treatment or inhibition of (i) dental diseases such as caries, gingivitis and periodontal disease, (ii) rarefying bone diseases such as osteoporosis and osteomal acia and ( iii) diseases re l ating to malabsorption of minerals. Accordingly, the present invention provides a composition comprising a peptide or a salt thereof in accordance with this invention and a h siolo ical ly acceptable diluent. The composition may be in the form of a pharmaceutical composition. The composition may be orally ingestible. A mixture of phosphope tides and /or their salts may be used in the composition. In this instance it is preferred that those containing tha sequence A -B-C-D-E abo ve predomina e . The phosphopeptide or mixture of phos ho epti es is preferably substantially pure at least to the extent of not containing unpalatable impurities. The fol lowing hospho eptides have been found to be useful in the compositions of the present inveπtioπ:- T1.Glu-flet-Glu-Ala-Glu-Psβ-Ile-Pse-Pse-Pse-Glu-Glu-ϊle-Val- Pro-Asn-Pse-Val-Glu-Gln-Ly s , T2.Glu-Leu-Glu-Glu-Leu-Asn-Val-Pro-Gly-Glu-Ile-Val-Glu-Pse- Leu-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Thr-Arg, T3.Asn-Thr-Plet-Glu-His-Val-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Ile- Pse-Gln-Glu-Thr-Tyr-Lys, T4.Asn-Ala-Asπ-Glu-Glu-Glu-Tyr-Ser-Ile-Gly-Pse-Pse-Pse-Glu- Glu-Psβ-Ala-Glu-Val-Ala-Thr-Glu-Glu-Val-Lys, and T5.Glu-Gln-L.eu-Pse-Pth-Pse-Glu-Glu-Asn-Ser-L.ys. The amino acid symbols are as fol lows : Pse- hosphoserine, Ser-Serine, P h -pho sp h o t hreo nin e , Thr- threoniπe, Glu-glutamate, A3p-aspartate, Ala-alanine, Asn- asparagine, Gln-glutamine, Gly-glycine, Arg-arginine , His- histidine, 11 e-i so 1 euc in e , Leu-leucine, Lys-lysiπe, fl e t - ethioπine, Pro-proline, Tyr-tyrosine , Val-valiπe. The hospho eptide may be made syntheti ally by chemical synthesis or genetic engineering or can be extracted from naturally occurring material. Because of cost considera ions it is currently more economic to extract the phosphopepti e from casein and in particular from alpha-s casein or beta-casein. Phosvitin may also be used as a source of the peptide. Further, phosphoproteins in cereals, nuts and vegetables particularly in bran hus s or sheaths may be used to produce the peptide above. In particular, rice, wheat, oat, barley or rye brans. Soybean and meat contain phospho roteins which may be of use in obtaining the peptide above. Casein and in particular alpha-s casein or beta-casein or salts thereof such as sodium caseinate contain pαlypeptides which can be cleaved to simpler peptides. Such cleavage may be effected by digestion, such digestion may be chemical or proteαlytic. It is presently preferred to digest casein with one of trypsiπ, pepsin, ch o t r y p si n , papain, thermolysin or pronase. Of these, trypsin is preferred. The digested casein can be fractioned .i to peptides including the sequence A-8-C-D-E and other peptides. The presence of said other peptides is not deleterious to efficacy, however, certain of said other peptides have objectionable taste and accordingly if any of said other peptides are to be included it is preferable to remove those having objectionable taste. In general , those of said other peptides having objectionable taste seem to be hydrophαbic. The f ol lowing peptides have been f ound to have objectionable taste:- ' 1. Glu-Val-Leu-Asn 2. Asn-Glu- Asn-Leu-Leu 3. Ala-Pro-Phe-Pro-Gln-Ual-Phβ-Gly 4. Leu-Arg-Phe 5. Phe-Phe-Val-Ala-Pro-Phe-Pro-Glπ-Val-Phe-Gly-Lys 6. Leu-Arg- eu 7. Phe-Tyr-Pro-Glu-Leu-Phe (Glu-g luta ate; Val-valine; Leu-leucine; Asn-asparagine ; Ala-alanine; Pro-proline; Phe-phen la 1 aπiπe; G1n-g 1 utaminej Gly-glycine; Arg -Argininej Lys-lysine; Tyr-tyrαsine.) Preferably the peptide is one exhibiting a reduction in hydroxy apatite dissolution rate of at least 15X under the test conditions defined herein. Preferably the peptide is one exhibiting a reduction in hydroxy apatite dissolution rate of at least 26$ under the- test conditions defined herein. Preferably, the peptide is one exhibiting a reduction in hydroxy apatite dissolution rate of at least 20% under the test conditions defined herein. Preferably, the peptide is one exhibiting a reduction in hydroxy apatite dissolution rate of at least 32< under the test conditions defined herein. Preferably, the peptide is present as 0.01 to 10!. by weight. Preferably, the peptide is present as 0.01 to 5% by weight . Preferably , the peptide is present as 0.01 to 2% by weight. The composition of this invention may be in the form of a comestible such as foodstuff or confectionery, dentifrice, tablet or comprise a pharmacologically acceptable vehicle or solution of suspension for topical application to the teeth or gingival tissues or a mouthwash. Other modes of ad inis e ing the peptide would be acceptable if physiologically or pharmacologically acceptable. Of particular interest as compositions are chewing gum, breakfast foods, ice-cream and other frozen confectionery, confectionery, sweets and cakes as these are all known as caries problem materials. Similar considerations apply to other potentially cariogenic food components. Also of particular interest are dentifrices, αuthwashes and preparations for topical application to teeth and gingival tissue and enteric capsules for the treatment of bone disorders and mineral alabsorption . Also of interest is the use of compositions in accordance with this invention in respect of dental treatment of cavities. In this last respect, there appears to be evidence of r e iner a 1 i z a t i on of incipient lesions which are considered to be a pre-cavity condition. However, there is also evidence to indicate that application of compositions in accordance with this invention to the surfaces of actual cavities and to surfaces of teeth produced by removal of decay material from actual cavities or by fracture is beneficial. Since a topical application of a composition in accordance with this invention which is an aqueous solution to surfaces of actual cavities or surfaces of teeth produced by removal of decay material from actual cavities or by fracture is unlikely to have long term effect, we have further sought to provide compositions which might have the desired long term effect. Accordingly, the present invention also provides a composition in accordance with this invention and adapted to remain in contact with a tooth surface over a prolonged period. The invention also provides methods and means for maintaining compositions in accordance with this invention in contact with a tooth surface over a prolonged period. In this last respect a prolonged period should be interpreted in accordance with the effect desired and the time taken to achieve sufficient of that effect to be of value. However, in some instances that prolonged period may be as short as one day but is more preferably a period of weeks or months. In one instance a tooth cavity is coated with a composition in accordance with this invention and the cavity is closed to restrict escape of the composition. Such closure may be effected by capping or use of dental cavity filling compositions. In another instance the composition is so formulated as to be adapted to remain in place for a prolonged period. In this instance the composition of the invention may form part of a dental filling composition. Accordingly, the present invention also provides a dental filling composition comprising a phosphopeptide of formula A-B-C-D-E as defined above and a carrier therefor adapted to adhere the composition to a tooth surface. Such a dental fil ling composition may contain dental fil ling materials known per se including amalgams and settable polymers. Of particular interest are dental filling compositions which contain calcium. The calcium is desirably in the form of calcium phosphate or hydroxyapatite . The phos hope ides for use in the invention can be extracted in a number of ways but the use of a fractionation technique is generally preferred. The phosphopeptides can be extracted by fractionation based on molecular size or charge cha acte istics. Due to the unique negative charge density and divalent metal ion sequestering ability of the peptides conferred by the active sequence A-B-C-D-E as defined, the preferred fractionation procedure is anion exchange c h om a t o g aph y or selective precipitation or a combination of both. The f o l l owing procedure i l lustrates one mode of extraction. £x.£r £i.i£H Ei2£Sii-i£≤ IΛ An example of the phosphopep ides are those produced by a tryptic digestion of bovine milk casein. The digestion of whole sodium caseinate or fractions (alpha-S or beta) produced by selective precipitation (Zittle, CA. and Custer J.H.; J. Dairy Sci 4SL 1183-1189, 1963) is carried out using a protein; trypsiπ ratio of 50:1 in 20 m fl Trie HC1 pH 8.0, 2.5mfl NaC1 at 37°C for 1 h. The peptides were fractionated using a "Pharmacia FPLC system with a flono 0 HR 5/5 column and eluted with a NaC1 gradient; Buffer A 20mfl Tris HC1 pH 8.0, 2.5mfl NaC1 ; Buffer 8 20 ml"! Tris HC1 pH 8.0, 500mfl NaC1 , gradient 0 -100X Buffer 8/30 in; flow rate 1m1/min. Fractions were washed and concentrated using an A icαn Ul rafiltration Cell with a UflOS filter. The peptides ware identified using a Uater Associates PICO-TAG amino acid analysis system using phenylisothiocyanate amino acid e i a t is a i on. Phosphate was measured by the method of Itaya and Ui (C1 in, Chim. Acta. 14:361 -366, 1960). The peptides were sequenced (after the removal of phosphate by alkaline phosphatase) using manual Edman degradation and the resulting PTH-amino acids identified using reverse phase HPLC on a Zorbax 00S column 25x0.46 cm (OuPont). The fol lowing phosphopep ides were individua l ly obtained from a tryptic digestion of sodium caseinate using the above procedure. T1.Glu-flet-Glu-Ala-Glu-Pse-Ile-Pse-Pss-Pse-Glu-Glu-Ile-Val- Pro-Asn-Pse-Val-Glu-Gln-Lys. T2.Glu-Leu-Glu-Glu-Leu-Asn-Val-Pro-Gly-Glu-Il3-Val-Glu-Pse- Leu-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Thr-Arg. T3.Asn-Thr-flet-Glu-His-Val-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Ile- Psβ-Gln-Glu-Thr-Tyr-Lys. T4.Asn-Ala-Asn-Glu-Glu-Glu-Tyr-Ser-Ile-Gly-Pse-Pse-Pse-Glu- Glu-Pss-Ala-Glu-Val-Ala-Thr-Glu-Glu-Val-Lys. T5.Glu-Gln-Leu-Psa-Pth-Pse-Glu-Glu-Asn-Ser-L.ys. In addition the following peptides were also obtained: Tδ.Asp-Ilβ-Gly-Psβ-Glu-Pse-Thr-Glu-Asp-Gln-Ala-flet-Glu-Asp-

Ile-Lys.

T7.Val-Pro-Gln-Leu-Gln-Ile-Val-Pro-Asn-Pse-Ala-Glu-Glu-Arg.

T8.Thr-Val-Asp-flet-Glu-Pse-Thr-Glu-Val-Phe-Thr-Lys.

T9.Leu-Pth-Glu-Glu-Lys.

The peptides T1 ,T6 and T7 were also obtained from a TPCK-tryptic digest of a1pha₃^ -caseinate(comprising alpha_a1 and alpha_so). Peptide T2 was also obtained from a TPCK- tryptic digest of beta-caseinate. Peptides T3, T4, T5, T8 and T9 were also obtained from a TPCK-tryptic digest of a lpha₃2~caseinate (comprising a 1 pha₃2 -a 1 pha_3j . alpha_g4 and alpha g). The amino acid symbols are as fol lows: Pse- phosphoserine, Ser- . serins, P h - ph o sp h o th r e o π in e , Thr- threonine, Glu- Glutamate, Asp- aspartate, Ala- alanine, Asn- asparginβ, Gin- gluta ine, Gly- glycine, Arg- arginiπe. His- histidine, lie- isoleucine, Leu- leucine, Lys- lysinβ, flet - ethionine, Pro- proline, Tyr- tyrosine, Val- valine.

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The fol lowing procedure il lustrates one mode of selective precipita ion.

A solution of sodium caseinate was digested with trypsin (50:1, casein : tryp sin) for one hour at 37°C with the pH maintained at 8.0 by the addition of NaOH. HC1 (0.11-1) was then added to the solution at room temperature to pH 4.7 and the resulting precipitate removed. Bad, was added to the supernatant to a level of 0.25!. w/v followed by an equal volume of absolute ethanol and the resulting precipitate was removed and dried. The precipitate was dissolved in one tenth the original volume of water (to f acilitate dissolution the pH was raised with NaOH) and the solution acidified to pH 3.5 with 1 fl HC1. An equal volume of acetone was added and the precipitate removed and dried. The precipitate was then redissolved in H^O and acidified to pH

2.0 by addition of HC1. The resulting precipitate was removed and discarded and the supernatant was adjusted back to pH 3.5 with NaOH and an equal volume of acetone was added. The resulting precipitate was collected, redissolved in water and H₂S0₄ added to precipitate 8aS0₄ which was discarded. The supernatant was then dia l ysβd and lyophylised or spray dried. A mixture of 5 phosphopeptides were obtained with this procedure. The following are the phosphopeptides obtaiπed:- T1.Glu-flet-Glu-Ala-Glu-Pse-Ile-Pse-Pse-Pss-Glu-Glu-Ile-Val- Pro-Asn-Pse-Val-Glu-Gln-Lys . T2.Glu-Leu-Glu-Glu-Leu-Asn-Val-Pro-Gly-Glu-Ile-Val-Glu-Pse- Leu-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Thr-Arg. T3.Asn-Thr-flet-Glu-His-Val-Pse-Pse-Pse-Glu-Glu-Ser-Ile-Ile- Pse-Gln-Glu-Thr-Tyr-Lys. T4.Asn-Ala-Asn-Glu-Glu-Glu-Tyr-Sar-Ile-Gly-Pse-Pse-Pse-Glu- Glu-Pse-Ala-Glu-Val-Ala-Thr-Glu-Glu-Val-Lys. TS.Glu-Gln-Leu-Pse-Pth-Pse-Glu-Asn-Ser-Lys. The ratio of the phosphope ides ( T1 : T2 : T3 : T4 : T5 ) in the final preparation depends on the starting material and conditions of hydrolysis. Digesting sodium caseinate with TPCK-trypsin yields largely T2 with small amounts of T1 , T3 and T4. However, T2 shows greater lability than the other peptides such that more rigorous digestion as occurs with some commercia l casein digests yie l ds a preparation containing largely T1 with small amounts of T3 and T4. If in lieu of sodium caseinate, alpha s1 -casein is used ^'for this procedure pure T1 is obtained. With beta-casein as the starting material pure T2 is obtained. The most common sequences of the active peptides is the pentapeptide P se -P se- s e- G 1 u - G 1 u . The spacings of the phosphate and carboxyl groups in a beta -conformation of this pentapeptide are shown in Fig 1. The 6.88 Angstrom spacings of phosphates and carboxyls allows specific attachment to calcium atoms along the c-axis of h y dr o y a p a t i e crystal s. This pentapeptide sequence occurs in peptides T 1 to T4 and occurs modif ied in peptide T5 - s e - h -P s s - G 1 u - G 1 u f o l l owing a conser v ati v e substitution of phosphothreonine for phosphoserine. Conservative substitutions within the active sequence wou l d b e phos hoth eonine and to a l esser extent p h o s h o t r y r os in e or p h o e hoh i 3 i di n e for phos hoserine al though phosphoserine is preferable. Another possib le substitution for phosphoserine would be glutamate or aspartata but again phosphoserine is preferable. A possible substitution for glutamate is aspartate.

The active peptides can sequester calcium phosphate and other salts of divalent metal ions. One mole of T1 binds 16 mole of CaHPO^ such that a 10mg/ml solution of T1 at pH 7.0 can solubilize δQmfl CaHPO^ producing a mstastable supersaturated solution with respect tα calcium phosphate species. With chloride as the counter ion one mole of T1 binds only 5 mole of Ca⁺⁺ binding only to serine phosphates. One mole of T1 with about 16 mole of CaHPQ^ bound (A.W. 4883) will henceforth be referred to as calcium phosphate T1. An important chemical feature of calcium phosphate T1 is that above 2% w/v in water the composition is a thixotropic gel. T1 -T5 have been shown to be potentially anticar iogenic using the following test procedures: l£l£ li Hydroxyapatite Dissolution Rate Assay.

This test is a modification of a test procedure already described (Reynolds, E.C., Riley, P.F. and Storey, E. Calcif. Tiss Int 34:s52-s56, 1982). The purpose of this test is to determine the effect of the peptides on hydroxyapatite dissolution and in this respect since tooth enamel is largely composed of hydroxyapatite it is believed that useful comparisons can be made.

Double distilled, deionized water (18 mega ohms/cm) was used throughout. Analytical reagent grade chemicals were obtained from Ajax Chemicals, Australia. Hydroxyapatite- spheriαdal was purchased from BOH. A ch o a ogr aphy column containing 0.1 g of hy roxyapatite beads was used for the de iπera 1 isation assay. Tris 5m fl, pH 8.3 containing SOmfl

NaC1 was used as the column buffer at 2Q°C and was pumped through the column at a rate of O.lml/mln. A peptide solution 0.1mg/ml of buffer was applied to the column and 0.2ml fractions were collected before and after peptide application and assayed for total calcium, phosphate and peptide. From these values a rate of dissolution (nmol calcium or phosphate per min) for each 0.2ml fraction was obtained . Phosphope tides T1 -T5 al l decreased hy rox a a ite dissolution rate by about 32 . Phosphopeptides T5-T9 ware found to be much less effective. F luoride plus phosphopeptide T 1 ga ve a combined reduction in hydroxyapatite dissolution (40{ reduction). The phos hopepti e T1 caused a 50JJ greater retention of fluoride in the hydroxyapatite column. This work shows that these phosphopeptides bind to hydroxyapatite and reduce the minerals dissolution rate and enhance the retention of fluoride in the crystal matrix. The reduction in h droxyapatite dissolution was related to the phosphoserine content and spacings within the peptides. l £l L Intra-Oral Caries Test. The a ic a r i o g e n ici y of phos hopeptide T1 was determined using a modification of the intra-oral caries test of Kσulourides and Ostrαra (Caries Res. 10:442-482, 1976). Enamel slabs were inset in a removable intra-ora appliance to simulate an approxi al area. This was done on both sides of the removable appliance (left and right). The appliance was worn to allow plaque accumulation in the simulated approxima l areas. Eight times a day the appliance was removed and placed in a solution at 37°C. The solution was 2% w/v sucrose, 2i w/v glucose, 140 fl KC1 , 20mfl NaC1 at pH 7.0. Twice a day the right side enamel slabs received exposure to a solution containing 1,8{ w/v calcium phosphate T1 in 140 mfl KC1 , 20 mfl NaC1 at pH 7.0, while the left side received only the salt solution. At the completion of the experiment the enamel slabs were removed, sectioned and subjected to mi c r o r a di o r a hy and micrσh a r dnes s testing. The mi cr ora d i o g r a p hy showed that the slabs exposed to the sugar-salt solution (left-side) had sub-surface, caries-like lesions. However, the slabs exposed to the sugar-salt solu ion and the peptide T 1 solution twice a day showed no caries-like changes. The results were confirmed by icrohar dπess analysis. Plaque was also taken from bath sides of the appliance and analysed for calcium phosphate, serine phosphate and peptide T1 using a competitive, quantit i e, en z y e - 1 i n βd i mu no s or bent assay (ELISA) uti l ising monoclona l aπtipsptlde T1 antibodies. This showed that the plaque an the right side of the appliance exposed twice a day to the peptide T1 solution contained the peptide at a level of at least 0.4$ w/wβt wt of plaque and the level of calcium phosphate had increased 2-4 fold. This work shows that peptide T1 is incorporated into plaque thereby increasing the plaque level of calcium and phosphate so inhibiting the caries process. This method of incorporation and accumulation in dental plaque can be used to carry re inera 1 ising and antibacterial ions into plaque and enamel e.g. Ca, 0₄, FPO-_j, Zn, Cu, Sn, Ag, Al , Fe and La. l£ at 3 - Iπtra-Oral Remineralisation An intra-oral appliance ^similar to that used In the previous test procedure was used except that the enamel slabs had been previously exposed to a d emin e r a 1 i s ing solution to produce two sub-surface de inera 1 ised lesions in each slab. The deminera 1 ising solution was a 0.1 fl lactate buffer pH 5.0 containing 500 mg/L hyd oxyapati e and 1 $ agar. The appliances were warn by subjects for 10 days. Twice each day the appliances were removed and a drop of r e i n er a 1 i s i ng solution was placed on the enamel slabs on the right of the appliance. The left-side enamel slabs served as cαπtrols. After 10 days the enamel slabs were removed, sectioned and subjected to micror adiαgraphy. The amount of mineral deposited back into the sub-surface l esions was determined using microdensitσmetry. The rsminera l ising solution containing 1.8$ w/v ca lcium phosphate 1 pH 7.0 returned 57$ of the minera l l ost compared with 13$ by saliva alone. l£ϋi £ " Plaque pH Fall Subjects refrained from oral hygiene for 3-5 days then rinsed with a 5$ sucrose solution for 1 min. Plaque samples were remo v ed and pH was measured using the one drop technique. After apprαxi aely 5 min tha pH fal l to around 5.0. However, if the subjects rinsed with a solution containing 1.8$ w/v calcium phosphate T1 , pH 7.0 15 min before rinsing with the 5$ sucrose solution the plaque pH did not fal l below 6.7, demonstrating significant pH buffering by the calcium phosphate T1. iiih i l e t h e p recis e m echanism b y which t he phosphope tides exhibit ant i ca r iogenic activity is not known, the following speculative theories have been put forward but are not to be taken as binding or limiting. The phosphopeptides may accumulate in plaque and enamel, buffer plaque acid, prevent enamel deminera 1 isat ion and enhance re inera lisation. The small molecular weight of the phospho eptides may al low penetration and accumulation in p laque and enamel pores. The phosphopeptides, due to the appropriate spacing of serine phosphate residues, may bind . to tooth enamel mineral and prevent de iner a 1 i sa t ion. The peptides may also carry calcium and phosphate (f 1 uorophosphate on modification) into plaque and enamel, in an appropriate form, possibly allowing spontaneous r e in er a 1 i sa t ion. The phosphoserine residues may also buffer plaque acid. The phosphopeptide may also carry antibac erial metal ions e.g. Zn, Cu, Sn, Ag, Al, Fe and La into plaque and in this way have an antiplaque and antigingi v itis effect. The metal ions are carried by the phosphopeptides primarily due to the phosphose ine residues. Phosphopeptides may bind to plaque bacteria and inhibit sugar utilisation. The ability of these peptides to sequester calcium phosphate can be utilised in the tr-eat ent of various rarefying bone diseases. These peptides can significantly increase the absorption of calcium, phosphate and iron in the gut. Hence, pharmaceutical vehicles (e.g. enteric capsules) or foods containing calcium phosphate T1 and ferrous phosphate T1 can be used for the treatment of os teopor αsis/os teo alac ia and anaemia. Applicants have formulated various compositions in accordance with this invention as follows. In general, the compositions contain f rom 0.01 -10$ by weight of phosphopeptide. Example 1. Flour: In a device for mixing dry substances, 1$ by weight of calcium phosphate T1 was blended with flour. Example 2. Cereal: A breakfast cereal was sprayed with a solution of calcium phosphate T1 in water. The cereal f lakes were then dried to produce a finished product containing 1$ calcium phosphate T1. Example 3. Bread: 1 $ by weight of calcium phosphate T1 was added to the flour during the mixing of ingredients for the manufacture of bread. Example 4. Cake mix: 1 $ by weight of calcium phosphate T1 was added to the dry ingredients in the preparation of a cake mix. Example 5. Confectione y In the preparation of confectionery 1$ by weight of calcium phosphate T1 was added to the final mixture. Example 6. Biscuit: In the preparation of a b i s cui t /mi x t ur e 1$ by weight of calcium phosphate T1 was added to the other dry ingredients during mixing. Example 7. Beverage: A beverage was prepared in which 0.1$ weight of calcium phosphate T1 had been dissolved. Example 8. Tablet: A tablet was made containing 10$ by weight of calcium phosphate T1 together with excipients being flavouring matter and binding material. In preparation of a typical dentifrice within the scape of this invention, the requisite salt and salts of the selected phospho eptide are incorporated into dentifrice compositions in any suitable manner depending on whether a powder, paste or liquid preparation is tα be produced. For this purpose appropriate preparations of s u r f a c e - a c t i v e agents, binders, flavouring materials and other excipients required to achieve the required form of dentifrice are added . The invention is further illustrated by the following examples: Example 9. Tooth paste: A toothpaste was prepared having the following composition: Calcium phosphate T1 5.0$ by weight CflC 7flF 1.0$ " ^■ Saccharin 450 0.2$ " " Glycerin (8. .) 25.0$ " " Sodium lauryl sulphate (Empicol 0919) 5.0$ " " Sodium beπzoate 0.5$ " " Flavour 9/693090 0.8$ " " Calcium phosphate 1.0$ " " Mater Oeionised 39.5$ " " Thixosyl 333 9.5$ " " Syloid AL-1 12.0$ " " Titanium Dioxide 3328 0.5$ " ^■ Example 10. Toothpaste: A preparation as set out in Example 9 was repeated but with the addition of 0.2$ sodium fluoride in a suitable form. v Example 11. Toothpaste: A preparation as set out in Example 9 was repeated but with the addition of 0.4$ stannous fluoride in a suitable form. Example 12. Toothpaste: A preparation as set out in Example 9 was repeated but with the addition of 0.76$ monosodium f luor ophosphate in a suitable form. Example 13. Toothpowder: The following preparation was made : Calcium phosphate T1 5.0$ by weight Soluble saccharin 0.1$ " " Colour agent Trace Dibasic calcium phosphate 94.1$ " " Example 14. Toothpowder: A preparation as set out in Examp l e 13 was made but with the addition of 0.76$ monosodium fluorophosphate in a suitable form. Example 15. Liquid dentifrice: A preparation was made consisting of: Sodium alginate 1.4$ by weight Calcium phosphate T1 2.0$ " " Sodium lauryl sulphate 1.0$ " " Flavouring Trace Colouring Trace water 95.5$ ^B " Example 16. Liquid dentifrice: As far Example 15 but with 0.5$ sodium fluoride added. Example 17. flαuthwash: The following preparation was made : Calcium phosphate T1 2.0$ by weight Sodium fluoride 0.5$ " " Flavouring Trace Colouring Trace Water 97.5$ " " Example 18. Carbonated beverage: 0.1 $ by weight of calcium phos hopeptide T1 was added to a commercially available carbonated beverage. Example 19. Fruit juice: 0.1$ by weight of calcium phosphope tide T1 was added to a commercially available fruit juice. Example 20. Solution for topical application to teeth. Calcium Phosphate T1 2$ NaF 0.6 mfl ZnAcetate 0.1 mfl SrCl₂ 0.1 mfl (this solution may be formed into gel by increasing the amount of calcium phosphate T1 ) . Example 21. Oental filling material Calcium phosphate T1 5$ w/w Calcium phosphate 95$ w/w Poly eriser trace flade as a paste with water T h e p o l ym e r i s e r u s e d i n t h i s e x a m p l e w a s glutaraldehyde . Example 22. Oental filling material. Calcium phosphate T1 5$ w/w Calcium phosphate 70$ Acrylic polymer 25$ Catalyst for polymer trace Example 23. Topical Gel for the Treatment of hypersensiti e teeth. Calcium phosphate T1 4.0$ by weight SrF₂ 1.0$ by weight Flavouring Trace Water 95$ In the above calcium phosphate T1 was used for illustration but in lieu any appropriate phosphopeptide and/or salt might be used. Modifications and adaptations may be made to the above described without departing from the spirit and scope of this invention which includes every novel feature and combination of features disclosed herein. The claims form part of the disclosure of this

Claims (1)

1. - 17 - THE CLAIflS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A phospho e tide or a salt thereof the phos hopeptide having from 5 to 30 amino acids including the sequence A-B-C-D-E where A,B,C,D and E are independently phosphoserine, hos oth eoni e, phos ho yrosine, phosphohis i ine, glutamate and aspartate. 2. A phosphopeptide as claimed in claim 1, wherein A,B and C are inde endently phosphoserine, phosphothreonine, phosphotyrosine and phosphohistidine and 0 and E are independently phosphoserine, phosphothreonine, glutamate and aspartate. 3. A phosphopeptide as claimed in claim 1 , where A,B and C are phosphoserine and D and E are glutamate. 4. A phosphopeptide being one of Glu-flet-Gl u-A 1 a-G lu-Pse- Ilβ-Pse-Pse-Pse-Glu-Glu-Ile-Val-Pro-Asπ-Pse-Val-Glu-Gln-Lys. 5. A phosphopeptide being one of Glu-Leu-Glu-Glu-Leu-Asn- Val-Pro-Gly-Glu-Ile-Val-Glu-Psβ-Leu-Pse-Pse-Psβ-Glu-Glu-Sβr- Ile-Thr-Arg. 6. A phosphopeptide being one of Asn-Thr-flet-G1u-His -Va1 - Pse-Pse-Pse-Glu-Glu-Ser-Ile-Ile-Pse-Glπ-Glu-Thr-Tyr-Lys. 7. A phosphopeptide being one of Asn-A 1 a-Asn-G 1 u-G 1 u-G1 u- Tyr-Ser-Ile-Gly-Pse-Pse-Pse-Glu-Glu-Pse-Ala-Glu-Val-Ala-Thr- Glu-Glu-Val-Lys. 8. A phosphopeptide bein one of Glu-Gl n-Leu-Pse-Pth-Pse- Glu-Glu-Asn-Ser-Lys . 9. A phosphopeptide or a salt thereof as claimed in any preceding claim and in substan ially pure form. 10. A mixture of phosphope tides or salts thereof wherein a phosphopeptide or salt thereof in accordance with any one of claims 1-9 p edominates. 11. A composition comprising a phosphopeptide or a salt thereof in accordance with any one of claims 1-9 together with a ph siologically acceptable diluent. 12. A composition as claimed in claim 11 , wherein the phosphopeptide or salt thereof is present in the composition as 0.01 to 10$ by weight. 13. A composition as claimed in claim 11 , wherein tha phosphopeptide or salt thereof is present in the composition as 0.01 to 5$ by weight. 14. A composition as claimed in claim 11 , wherein the phosphopeptide or salt thereof is present in the composition as 0.01 to 2$ by weight. 15. A composition as claimed in any one of claims 11-14, wherein the diluent is a pharmaceu ically acceptable diluent. 16. A composition as claimed in any one of claims 11 -14, wherein the diluent is an orally ingestible material. 17. A composition as claimed in claim 16, wherein the diluent is a comestible. 18. A composition as- claimed in claim 17, in the form of a foodstuff or confection. 19. A composition as claimed in any one of claims 11-14, in the form of a toothpaste, tooth powder, dentifrice, mouthwash or preparation for topical application to teeth or gingival tissue. 20. A composition as claimed in any one of claims 11-14, in the form of a gel. 21. A composition as claimed in any one of claims 11-14, in the form of a dental filling composition. 22. A composition as claimed in claim 21 and additionally containing calcium phosphate or hydroxyapatite. 23. A method of obtaining a phos hopep ide in accordance with any one of claims 1 -9 which comprises fractionating a digest of casein, a 1 pha-s-ca sein , beta-casein or a salt thereof. 24. A pho.sphαpeptide in accordance with anyone of claims 1 - 9 in combination with calcium phosphate or hydroxy apatite. 25. A combination in accordance with claim 24, comprising about^'16 mole of CaHP0_ή per mole of phosphopep ide. 26. A combination in accordance with claim 24, or claim 25 in the form of a solution or gel. 27. A phosphopeptide or salt thereof , composition containing same αr a method of obtaining same substantiall as hereinbefore described with reference to any one of the Examples. 28 The articles, things, parts, elements, steps, features, methods, processes, compounds and compositions referred to or indicated in the s ecification and/or claims of the application individually or collecti el , and any and all combinations of any two or more of such.