42 



MACROMOLECULAR COMPLEXES 



r 



20 30 



IN MINUTES 



Fig. 22. Graph to illustrate the efFect of two proteolytic enzymes (trypsin, 

 Worthington, 2X recrystallized, and collagenase, Worthington) on the viscosity 

 of a typical solution of calfskin collagen in tris buffer, pH 6.9, in the presence 

 of 0.5M CaClj at 20 C. The enzymes were dissolved in the buffer solution and 

 the zero points obtained by measuring the viscosity of an aliquot of the collagen 

 solution when diluted with a volume of buffer equal to that used in adding the 

 enzyme. Note that while collagenase rapidly reduces the viscosity to a low 

 value, the effect of trypsin is a small but rapid reduction of the viscosity to a 

 high steady value and appears to be dependent on the enzyme concentration. 



addition of ATP is apparently a reliable criterion of the degree of 

 homogeneity of such solutions; when appreciable amounts of linear 

 polymers are present, addition of ATP produces precipitates which 

 are of a flocculent, fibrous character and do not settle even on 

 prolonged standing. These macroscopic characteristics are sup- 

 ported by electron microscope observations which consistently show 

 "strings" of segments, apparently arising from the "crystallization" 

 of TC macromolecules on the linear polymers present in the solu- 

 tion. On the other hand, the addition of ATP to acid collagen solu- 



