ANIMAL COLLAGENASE AND COLLAGEN METABOLISM 



673 



300 



200- 



TAIL FIN 



• CONTROL 



--0 THYROXIN Rx 



5 10 15 20 25 30 



HOURS AFTER PROLINE-H^ 

 Fig. 6. Specific activity of hydroxypioline isolated from the total collagen 



weight (including collagen and cells), the two curves would be 

 superimposable. These observations suggest that the rate of syn- 

 thesis of collagen was unchanged but the rate of resorption in- 

 creased. 



In the back skin there was an increase in both total and specific 

 activities in the metamorphosing animals as compared with the con- 

 trols ( Figs. 5 and 6 ) , indicating increased synthesis. 



Metabolism of the Extractable and Insoluble 

 Collagen Fractions 



Separation of collagen into soluble and insoluble fractions gives 

 us a more detailed picture of events. In Table II is found the amount 



