44 



MACROMOLECULAR COMPLEXES 



appreciably during this process. In contrast to this, exposure to 

 collagenases causes both the optical rotation and the viscosity to 

 decrease rapidly (Seifter et al., 1958). 



These results are compatible with the hypothesis that the enzy- 

 matic attack of pepsin and trypsin on collagen is confined to a 

 limited region at the ends of the TC macromolecule, yielding modi- 

 fied macromolecules whose length and internal helical configuration 

 remain essentially unaltered, but whose end-to-end polymerization 

 properties have been drastically modified (Fig. 23). The enzyme- 

 treated solutions yield single segments (whole monomeric type) 

 which are normal as judged by their band pattern on staining with 

 PTA. In contrast to this, the same collagen solutions fail to give 

 ordered aggregates of segment type after treatment with collage- 

 nase. Treatment with pepsin or trypsin also prevents the formation 

 of a water-clear gel on dialysis against distilled water, and almost 



I -CONTROL: NO TRYPSIN 

 n -0.01% TRYPSIN 

 m -0.05% TRYPSIN 

 12 - 0.1 % TRYPSIN 



0.8 



0.6 



0.4 



0.2 



40 60 



MINUTES 



Fig. 24. The efFect of treatment with trypsin (Worthington, 2x recrystal- 

 lized) on the thermal gelation of a 0.1 per cent solution of calfskin collagen 

 (tris buffer, pH 7, with 0.45M NaCI) at 34° C, after incubation with the 

 enzyme 6 hr at 20 C, as determined by the optical density at 430 m/x. 



