CREATIN AND CREATININ 



1 The creatin content of kitten muscle varies with the age of the animal. 



2 Various species of fish muscle were analyzed. The figures represent minimal and 

 maximal values. 



Denis (e) (1916) determined the creatin content of a relatively large 

 number of samples of human muscle and found it to vary from 360 to 421 

 milligrams per cent. The muscle of children and that of persons dying 

 of a wasting disease was usually found to be low in creatin. 



As the creatin content of muscle is determined by the Folin method 

 it was important to know if the color reaction was entirely due to this 

 substance. By first transforming the creatin in muscle extract into cre- 

 atinin and then quantitatively removing the latter by precipitation, Bau- 

 man and Ingvaldsen (a.) (1916) were able to show that creatin alone was 

 responsible for the Jaffe reaction. 



The Origin of Creatin 



A vast amount of experimental work has been done on this problem. 

 The only other guanidin derivative which has been found in the animal 

 body is the amino acid, arginiii (alpha amino, delta guanido valerianic 

 acid, (NH 2 C(:NH)NH CH 2 CH 2 CH 2 CHNH 2 COOH). Arginin has 

 been perfused and administered in various ways in order to see if it was 

 converted into creatin. On the whole the results have not been uniform 

 or conclusive. By analogy one might assume that arginin would first be 

 oxidized to guanidoacetic acid or glycocyamin (NH 2 C( :NH)NH-CH 2 



