656 



THE BIOCHEMISTRY OF B VITAMINS 



pyridoxine from the medium. 32 Pyridoxal phosphate fed with the diet is 

 similarly less active than pyridoxine, but when injected the two sub- 

 stances are equally active for rats. 45 



Table 36. Biological Activities of the Vitamin B 6 Group. 



, Activity, per cent of most active form . 



Organism 



Rats 



Mice 

 Chicks 



Tetrahymena geleii 

 Lactobacillus helveticus 

 Lactobacillus acidophilus 

 Lactobacillus casei 

 Streptococcus faecalis R 

 Streptococcus lactis L 101 

 Lactobacillus arabinosus 



Leuconostoc mesenteroides 

 Streptococcus lactis UT 

 Streptococcus lactis 374 

 Streptococcus mastitidis G-2 

 Streptococcus mastititis 97-B 

 Streptococcus zymogenes H69D5 

 Bacillus lactis acidi Bl-1 

 Clostridium perfringens 

 Clostridium welchi (B P6K) 

 Saccharomyces carlsbergensis 

 Saccharomyces cerevisiae GM 

 Saccharomyces oviformis 

 Ceratostomella ulrni 

 Neurospora sitophila 299 



° Injected in radial vein. Activities indicated are also the same for ability to promote blood regimenta- 

 tion in anemic dogs. 



b Injected intraperitoneally or fed by dropper; pyridoxal, pyridoxal phosphate or pyridoxamine are less 

 active than pyridoxine if fed in the diet. 



« Fed in diet. 



d Ability to utilize pyridoxal increased after first week. Xanthurenic acid excretion data support the 

 growth data. 



• Dose-response curves for pyridoxamine phosphate and pyridoxamine differ. Figures express extreme 

 variation in relative activity which increases as pyridoxamine is increased. 



/ Activity in stimulating growth, vitamin B 6 not essential for growth. 



"Activity in allowing growth to occur on indole in place of tryptophan. 



It is interesting to note that two organisms — a strain of Lactobacillus 

 helveticus and a strain of Lactobacillus acidophilus — require the phos- 

 phorylated forms of pyridoxamine or pyridoxal and cannot utilize pyri- 

 doxal, pyridoxamine or pyridoxine. Pyridoxamine phosphate is from 3 to 

 6 times as active as pyridoxal phosphate for these organisms. 



Most bacteria utilize either pyridoxal or pyridoxamine more effectively 

 than pyridoxine. The normal habitat of most of these organisms is of 



