16 PROTEIDS. 



2. Syntonin. 



Although this substance is merely the acid- albumin which results 

 from the action of acids on the globulin (myosin) contained in muscles, 

 and in its more obvious properties is at first sight identical with other 

 acid-albumins, it merits a short and separate description, not only on 

 account of its historical interest in the chemistry of muscles but also 

 because recent work has shewn it to be distinctly different from the similar 

 products of the action of acids on other proteids, and its properties and 

 reactions have been more fully studied than those of any other form of 

 acid-albumin. , 



Liebig, unacquainted with the existence of myosin in the dead muscle, was the 

 first to prepare it by the action of dilute (-1 p. c.) hydrochloric acid on the muscle 

 substance 1 , and he regarded it as the chief and characteristic proteid of muscles 

 (muscle-fibrin). Kuhne however shewed in his famous researches on muscle-plasma 2 

 that its formation is due to the conversive action of the acid on myosin. 



Preparation. By the action of 0-1 p.c. hydrochloric acid on pure 

 myosin (see below), or by treatment of finely chopped and tliorouglily 

 washed muscle substance, preferably from the frog, with the same 

 acid. It may be precipitated from its solution by neutralisation, and 

 freed from salts by washing, but in this case care must be exercised as to 

 the extent of the washing, since syntonin is distinctly altered by the 

 prolonged action of water, especially as regards its solubility in dilute 

 acid and lime-water 3 . 



The reactions specially characteristic of this substance and its 

 distinction from other forms of acid-albumin and from alkali-albumin 

 are indicated in the following statements 4 . 



1. It is soluble in lime-water, and this solution is coagulated, 

 though incompletely, by boiling (Kiihne). 



2. It is insoluble in acid phosphate of soda (^N"aH 2 P0 4 ), other 

 acid-albumins are soluble (Mb'rner). In presence of this salt it does 

 not pass into solution on the addition of alkali until the whole of the 

 acid phosphate has been converted into the neutral (Na 2 HPO 4 ). In 

 this respect it differs from alkali-albumin, which is soluble under the 

 same conditions long before the conversion of the acid into the neutral 

 phosphate is complete. 



3. It is soluble in dilute sodium carbonate. 



4. When precipitated from its acid solution by neutralisation the 



1 Annalend. Chem. u. Pliann. Bd. 73 (1850), S. 125. 



2 Ueber das Protoplasma, Leipzig; 1864, S. 15. 



3 Kiihne, loc. cit. S. 16. Sander, Arch. f. Physiol Jahrg. 1881, S. 198. 



4 See Morner, loc. cit. 



