I I Q PHYSIOLOGICAL CHEMISTRY. 



but insoluble in neutral fluids. The metaproteins have generally 

 been termed albuminates, but inasmuch as the termination ate sig- 

 nifies a salt it has always been somewhat of a misnomer. 



Two of the principal metaproteins are the acid metaprotein or 

 so-called acid albuminate and the alkali metaprotein or so-called 

 alkali albuminate. They differ from the native simple proteins 

 principally in being insoluble in sodium chloride solution and in not 

 being coagulated except when suspended in neutral fluids. Both forms 

 of metaprotein are precipitated upon the approximate neutraliza- 

 tion of their solutions. They are precipitated by saturating their 

 solutions with ammonium sulphate, and by sodium chloride, also, 

 provided they are dissolved in an acid solution. Acid metaprotein 

 contains a higher percentage of nitrogen and sulphur than the 

 alkali metaprotein from the same source, since some of the nitro- 

 gen and sulphur of the original protein is liberated in the forma- 

 tion of the latter. Because of this fact, it is impossible to trans- 

 form an alkali metaprotein into an acid metaprotein, while it is 

 possible to reverse the process and transform the acid metaprotein 

 into the alkali modification. 



EXPERIMENTS ON METAPROTEINS. 



ACID METAPROTEIN (ACID ALBUMINATE). 



Preparation and Study. Take 25 grams of hashed lean beef, 

 washed free from the major portion of blood and inorganic matter, 

 and place it in a medium-sized beaker with 100 c.c. of 0.2 per cent 

 HCL Place it on a boiling water-bath for one-half hour, filter, 

 cool and divide the filtrate into two parts. Neutralize the first part 

 with dilute KOH solution, filter off the precipitate of acid meta- 

 protein and make the following tests : 



1 i ) Solubility. Solubility in the ordinary solvents (see page 23 ) . 



(2) Millon's Reaction. 



(3) Coagulation Test. Suspend a little of the metaprotein in 

 water (neutral solution) and heat to boiling for a few moments. 

 Now add 1-2 drops of KOH solution to the water and see if the 

 metaprotein is still soluble in dilute alkali. What is the result 

 and why? 



(4) Test for Loosely Combined Sulphur (see page 102). 



Subject the second part of the original solution to the following 

 tests : 



