196 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



In another procedure (538) the crystalline salt of streptomycin and 

 /)-(2-hydroxy-l-naphthylazo)-benzenesulfonic acid is prepared from 

 streptomycin HCl, and orange II. The salt has an activity of 300 

 Mg/mg. Crystalline streptomycin sulfate was found to have an activity 

 of 520 ng/mg. 



On chromatographic purifications, streptomycin concentrates yielded 

 a crystalline double salt of streptomycin trihydrochloride and calcium 

 chloride (Figure 19). This preparation showed that streptomycin has 

 the composition CsiHg^.ggN^Ois- The double salt is characterized by 

 constant biological, chemical, and physical properties. It is more satis- 

 factory than the hydrochloride which is obtained by precipitation. The 

 double salt can be prepared from streptomycin hydrochloride or from 

 the crystalline streptomycin helianthate. A cryoscopic molecular weight 

 determination on streptomycin trihydrochloride in water gave about 

 800 for the free base, necessary corrections having been made for the 

 chloride ion and the non-ideal cryoscopic behavior of the trivalent 

 streptomycin ion (712). 



Further studies on the chemistry of streptomycin revealed the fact 

 that it has the general constitution of a hydroxylated base (streptidine) 

 attached through a glycosidic linkage to a nitrogen-containing disac- 

 charide-like molecule. The latter group of the streptomycin molecule 

 contains a free or potential carbonyl group and a methyl-amino group 



(85). 



The reaction of the streptomycin with one molecule of water can be 

 presented as follows: 



C.,H3,_3oN,0,, + H,0 ^ CsH.sNeO, + Ci3H,,_,3NO, 

 Streptomycin Streptidine Streptobiosamlne 



Ci3H,3NO, -f H3O -> CeHioO, + C,Hi,N05 



Streptobiosamine Streptose N-methyl-a- 



/-glucosamine 



The basic nitrogen atom in the streptobiosamine is not present as a 

 primary amino group. The streptomycin molecule was presented 

 graphically as follows : 



