114 INTRODUCTION TO IMMUNOCHEMICAL SPECIFICITY 



in glucose. They further conckided that antigen 4 contains groupings 

 similar to those present in the galactomannans. These polysaccharides 

 contain long chains of mannose linked 1^4, with occasional side 

 chains consisting of galactose linked 1^6, as shown in the following 

 scheme : 



galactose galactose 



(1-6) 



(1-6) 



— (1-^4) mannose (1— »4) — mannose — (1-^4) mannose (l->4) — 

 It is evident that the precipitability of anti-4 antibodies by these 

 galactomannans is due to their specificity for a terminal galactose, a 

 galactose-mannose group, or a chain of mannose linked 1— >4. The 

 last possibility is eliminated by the fact that oxidized paratyphoid 

 polysaccharide still precipitates this antibody, for mannose linked 

 1^'4 would be destroyed by periodic acid oxidation. The probability 

 that the cross-reaction is due to a terminal galactose was diminished 

 by the failure of Heidelberger and Cordoba (1956) to obtain cross- 

 reactions with other polysaccharides containing terminal galactoses. 

 Also, periodic acid oxidation would destroy a terminal galactose, yet 

 the oxidized polysaccharide is still able to absorb out the anti-4 

 antibodies. One is, therefore, led to conclude that the grouping com- 

 mon to antigen 4 and the galactomannans is the galactose-mannose 

 grouping. But, since antigen 4 terminates in a nonoxidizable sugar 

 and the only such sugar present is abequose, the terminal portion 

 of antigen 4 may be : 



abequose — galactose — mannose 



Staub et al. (1959) were able to detect a weak cross-reaction be- 

 tween S. schottmuelleri and 5. nezvport owing to the terminal 

 abequose which forms part of antigen 4 in the former and part of 

 antigen 8 in the latter. This cross-reaction took place with horse 

 serum only, which suggested that the horse produces antibodies spe- 

 cific for the terminal sugar more readily than the rabbit does. 



In later work Staub et al. established the terminal sequence of 

 sugars in antigens 1 and 12 as : 



o-glucose — galactose — mannose — rhamnose 

 The linkages between the glucose and galactose are different in the 



