SECTION TWO 



The following are among those weakly stained (weakly " PAS- 

 positive "): 



Adenosine Cellulose 



Adenylic acid (muscle) Serum albumen 



Egg albumen Xanthosine 

 Glucose- 1 -phosphate 



The following are among those substances which do not take 

 up the stain at all and are, therefore, classed as " PAS-negative ": 



Deoxyribonucleic acid Inositol Ribonucleic acid 



Tryptophane is coloured brown (not red or pink), and is 

 " PAS-negative ". 



Notes: 



{a) The action of the periodic acid is to break the carbon bond 

 through 1,2-glycol groups or HO — C — C — NH2 groups, con- 

 verting these into dialdehydes, which are then available for 

 reaction with Schiff reagent. A positive Schiff reaction after 

 treatment with periodic acid or other oxidants is considered to be 

 specific for adjacent hydroxyl (or hydroxyl and amino) groups. 



{b) Readers requiring more detailed information regarding the 

 chemistry of the reaction should consult any one of the following 

 works: Gomori, G. (1952), Gurr, E. (1958a), or Pearse, A. G. 

 Everson (i960). Davenport, H. A. (i960), and Lillie, R. D. (1954) 

 also give a great deal of information on the application, limitations 

 and modifications of the PSA technique. 



(c) The confirmatory tests described below may be applied, if 

 desired, after the PAS reaction. 



References : 



Hotchkiss, R. D. (1948). 

 McManus, J. F. A. (1946). 



Diastase digestion test 



For differentiating between glycogen, mucin and starch 



Solution required: 



Diastase (animal or malt) . . i gm. 



Phosphate buffer solution pH 7-0, 100 ml. 



353 



