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The Relationship between Swelling of Hard Tissue Collagen in 

 Acid and Alkali and the Presence of Phosphate Cross-links 



W. M. McKernan, S. D. Dailly 



Research and Development Department, Gelatine Division, British Glues and Chemicals Ltd., 



London, England 



While the swelling characteristics of soft tissue collagens have been extensively- 

 studied (Bowes and Kenten, 1950 a, b) only recently has attention been directed to 

 similar studies of hard collagenous tissue. This latter work has arisen from the 

 observation that the solubility of dentine collagen is very much less than that of 

 corium collagen and this has been attributed to differences in the type or extent of 

 intermolecular stabilisation in these two materials (Veis and Schlueter, 1963). More 

 recently (Veis and Schlueter, 1964; Schlueter and Veis, 1964) it has been pro- 

 posed that specific phosphate diester bonds are involved in cross-linking dentine 

 collagen and that these esters are attached to the polypeptide chains through serine. 



Bovine bone collagen is, in many respects, similar to dentine collagen particularly 

 with regard to its physical organisation and the difficulty with which soluble com- 

 ponents can be extracted. Comparative chemical analyses show, however, that purified 

 bone collagen has a very much lower phosphorus content than dentine collagen and it 

 was, therefore, of interest to determine whether bone collagen follows a similar pH- 

 swelling relationship to dentine collagen and, if so, whether the intermolecular 

 stability could be attributable to similar phosphate diester covalent cross-links. 



