THE BETAINES AND THE VITAMINES 189 



lactic, the immediate origin of an attack being frequently traceable to 

 ingestion of some protein to which the individual in question has 

 become sensitized, e. g., the proteins in the sweat of horses, egg-white, 

 the proteins in strawberries or in pollen, or possibly proteins pro- 

 duced locally by bacterial infections. On the other hand asthmatic 

 attacks, originally anaphylactic, may frequently be seen in early 

 cases to pass through transitional stages into habitual reflexes, which 

 are thereafter elicited by any unusual stimulus, e. g., emotional excite- 

 ment or indigestion. The problem is therefore a many-sided one of 

 which the several factors are frequently difficult or impossible to 

 disentangle. 



Closely related to the amines which we have been considering are 

 the co-Amino-acids in which the a-amino-group which is so characteristic 

 of the amino-acids derived from proteins is absent, the ami no-group 

 being attached to a carbon atom which is remote from the carboxyl- 

 group. This results in greatly increased basicity of the amino-acid 

 so that these compounds resemble the amines in chemical behavior 

 rather than the amino-acids. They may be produced in putrefaction 

 by partial deaminization of a diamino-acid, as in the production of 

 6-Amino-valeric Acid from ornithine: 



H 2 N.CH 2 .CH 2 .CH2.CH(NH 2 )COOH + 2H = H 2 N.CH 2 .CH 2 .CH 2 .CH 2 .COOH + NH 3 



or they may result from partial decarboxylization of a dicarboxylic 

 acid, as in the production of 7-Aminobutyric Acid, from glutamic acid: 



HOOC.CH(NH 2 ).CH 2 .CH 2 .COOH = H 2 N.CH 2 .CH 2 .CH 2 .COOH + CO 2 



An important representative of this group of substances is Carnosine 

 which, next to creatine, is the most abundant nitrogenous base in 

 meat-extracts. It is present in horse-meat to the extent of 1.8 grams 

 per kilo. On hydrolysis it yields Histidine and /5-Alanine in equi- 

 molecular proportions. It is believed to be a dipeptide histidyl-/3- 

 alanine: 



CH = C CH 2 .CH.COHN.CH 2 .CH 2 COOH 



I 



N NH NH 2 



THE BETAINES AND THE VITAMINES. 



The Betaines are amino-acids in which the nitrogen atom is united 

 to methyl-groups in the place of hydrogen atoms. These substances 

 in the absence of water, form cyclic anhydrides which open up when 

 they are dissolved in water or unite with acids. Thus Betaine itself, 

 or Trimethylglycine has the formula: 



o 



(CH 8 ) 3 N< 



CH 2 



