MACROMOLECULAR AGGREGATES IN CALCIFICATION 71 



TABLE 2A 



Availability of €-NH2 Groups of Bone Collagen to FDNB 



as a Function of Their Mineral Content (Hand-cut, or 



"coarse," particles demineralized with EDTA) 



TABLE 2B 



Availability of e-NHi.. Groups ^o FDNB in Native Undecalcified Bones 



of Various Densities, in Order of Decreasing Density 



(Hand-cut, or "coarse,'" particles reacted for 48 hours) 



carboxyl groups (glutamic and aspartic acids) and the number of 

 guanidino groups (arginine) which were available also increased 

 with demineralization (Tables 3A, 4); (3) that the number of such 

 groups available in native bone of various kinds also varied in a 

 fashion similar to the e-NH. groups, and was also apparently de- 

 pendent on the density and packing of the specimen; and (4) that 

 the humber of reactive groups available in native bone varied with 

 the particle size: the finer the particle size of the bone samples, the 

 more groups that were available for reaction ( Tables 2C, 2D, 3B ) . 



