MACROMOLECULAR AGGREGATES IN CALCIFICATION 73 



TABLE 3B 



Availability of Guanidino Groups of Arginine to PTA as a Function 

 of Particle Size in Native Mineralized Bone 



/u mole of Arginine Available/g Collagen 

 Bone Source Coarse Powdered 



TABLE 4 



Availability of Carboxyl Groups to Methylation in Tv/o Species 

 of Bone as a Function of Mineral Content * 



( Note that the mineral contents of the native undecalcified bones are 



approximately the same although they have markedly different densities, 



fish < calf. ) 



* The number of groups available (for methylation) depends, 

 among other things, on the volume of solution used, normality of acid, 

 and time of exposure. Therefore, the figures do not represent the total 

 number of groups available, but only that number available under ex- 

 perimental conditions used. Since the two species of bones were 

 treated identically, the values obtained are comparable. Other experi- 

 ments have shown thai m hand-cut, coarse fish bone particles over 70 

 per cent of the theoretical number of carboxyl groups can be methylated. 



f Due to the HCl in the methylating media and not to EDTA. 



\ Analytical values varied but at the most were well under 70 

 fj. mole/g. 



In any event, determining the number of e-NH^, groups which are 

 available for reaction with FDNB will not show whether there is or 

 is not an electrostatic interaction between the e-NH. groups and the 

 mineral ion(s). In both instances (free or electrostatically linked 

 e-NHv groups), the FDNB would react with the e-NH. groups, in 

 the latter case by displacing the relatively weak electrostatic bond. 

 On the other hand, failure of the e-NH. groups to react with FDNB 



