CREATINE. 573 



p. m. and 0.71 p. m. respectively, which corresponds closely to the results found 

 by SCAFFIDI, BUGLIA and COSTANTINO for the striated muscle of the calf, namely, 

 0.58-0.68 p. m. According to RINALDI and SCAFFIDI 1 the lowest values for the 

 purine nitrogen occur in the striated muscles of the covering of polype, 0.436 

 p. m., then in fishes 0.595-0.82 p. m. and the highest 1.061 p. m. in birds. BUGLIA 

 and COSTANTINO have determined the nitrogen titratable with formol, and from 

 this determined the amount of monamino-acid nitrogen as well as diamino-acid 

 nitrogen in various animals. In oxen they found in the moist, striated muscle 

 0.18 p. m. monamino- and 0.40 p. m. diamino-nitrogen. In the heart the cor- 

 responding figures were 0.18 and 0.18 p. m. In percentage of the total nitrogen 

 the total amino-acid nitrogen in the striated muscle was 1.70 per cent and in 

 the heart 1 .48 per cent. 



The most extensively occurring nitrogenous extractives in the muscle 

 are creatine and carnosine. 



</NH 2 



Creatine, C4H 9 N 3 O2, C==NH , or methyl-guanidine- 



\N(CH 3 ).CH 2 COOH 



acetic acid, occurs in the striated as well as smooth muscles. In the 

 striated muscle of vertebrates the amount varies between 2.5 and 7 p. m. 

 It is also found in the brain, blood, transudates, amniotic fluid, and 

 sometimes also in the urine. 



Creatine may be prepared synthetically from cyanamide and sar- 

 cosine (methylglycocoll) . On boiling with baryta-water it decomposes, 

 with the addition of water, and yields urea, sarcosine, and certain other 

 products. Because of this behavior several investigators consider 

 creatine as a step in the formation of urea in the organism. On boiling 

 with acids, creatine is easily converted, with the elimination of water 

 into the corresponding anhydride, creatinine, C^yNsO, which is retrans- 

 formed into creatine by the action of alkali. 



The question as to the mutual relation of creatine to creatinine in 

 metabolism will be treated in Chapter XIV (urine). In this chapter, 

 besides the properties and reactions, we will discuss the question as to 

 the origin of creatine and its relation to the metabolism of the muscles. 



Of special interest in this regard, besides the relation between creatine 

 and muscle work which will be discussed below, is the question as to 

 the occurrence of free or combined creatine in the muscle. URANO by 

 the aid of dialysis experiments has shown the probability that the crea- 

 tine does not exist free in the muscle, but as a labile, non-dialyzable 

 combination. Nevertheless GOTTLIEB and STANGASSINGER claim by 

 various researches to have shown in the autolysis of muscles and other 

 organs,. that .creatine is first formed and then first changed into creatinine 

 by special bodies of an enzymotic nature, and then destroyed. SEEMANN 



1 v. Furth and Schwarz, Bioch. Zetschr., 30; Scaffldi, ibid., 33; Burian and Hall, 

 Zeitschr. f. physiol. Chem. 38; Buglia and Costantino, ibid., 81 and 82; Rinaldi and 

 Scaffidi, Bioch. Zeitschr., 41. 



