268 PYRIDOXINE AND RELATED COMPOUNDS 



The excretion of creatinine was higher in deficient rats than in control rats. 

 Martin'" showed that the toxicity of L-tyrosine was less in pyridoxine- 

 deficient animals than in control animals. 



A derangement in tryptophan metabolism is very common in vitamin 

 Be deficiency. Vitamin Be-deficient rats, or rats receiving desoxypyridoxine, 

 excrete more xanthurenic acid in the urine than do normal animals, when 

 they are fed tryptophan.''^ Such a derangement in tryptophan metabolism 

 is one of the earliest symptoms of vitamin Be deficiency in higher animals 

 and man.^^ This increased excretion of urinary xanthurenic acid by the 

 deficient rat is diminished by niacin supplementation.^" 



Sheppard and McHenry^^ found that in vitamin Be-deficient rats the 

 pyridoxine content of liver, kidney, and leg muscle was independent of 

 protein intake. With a constant protein intake, the pyridoxine concentra- 

 tion of liver is proportional to dietary pyridoxine concentration up to 25 

 7 per rat per day; the content of pyrodixine in the liver can also be in- 

 creased by keeping the dietary pyridoxine content constant and increasing 

 the protein level. Irradiation does not effect the concentration of vitamin 

 Be in the liver of normal or deficient rats.^^ 



Many enzyme systems which are intimately involved in the catabolism 

 of proteins are affected by a vitamin Be deficiency. The livers of vitamin 

 Be-deficient rats have only one-third the kynureninase activity of livers of 

 normal rats.''^ • '*^'"' The heart and kidney-cortex tissues of avitaminotic rats 

 had only 40 % transaminase activity of similar tissues from control animals; 

 however, the succinic acid oxidase activity of these deficient tissues was 

 80 to 90 % the activity of normal tissues.** The glutamic acid decarboxylase 

 activity of the brain of the vitamin Be-deficient rat is 50 % less active than 

 that of a normal brain.**'' The in vitro transfer of sulfur from homocysteine 

 to serine is retarded with liver extracts of vitamin Be-deficient rats; the 

 addition of phosphopyridoxal restores this transsulfurization enzyme sys- 



»7 G. J. Martin, J. Biol. Chem. 166, 389 (1946). 



38 S. Lepkovsky, E. Roboz, and A. J. Haagen-Smit, J. Biol. Chem. 149, 195 (19-13). 



3s L. D. Greenberg, D. F. Bohr, H. McGrath, and J. F. Rinehart, Arch. Biochem. 21, 



■ 237 (1949). 



^»M. Heimberg, F. Rosen, I. G. Leder, and W. A. Perlzweig, Arch. Biochem. 28, 



225 (1950). 

 " E. C. Sheppard and E. W. McHenry, /. Biol. Chem. 165, 649 (1946). 

 « M. L. MacFarhind, M. V. Peters, R. M. Halhxntyne, and E. W. McHenry, Am. J. 



Physiol. 163, 394 (1950). 

 « A. E. Braushtehi, V.. V. Gorvaclienkova,, and T. S. Va»\ihuvA, Biohhimiija U, 163 



(1948). 

 "* M. Mason and C. P. Rerg, ./. Biol. Chem. 195, 515 (1952). 



" S. R. Ames, P. S. Sarma, and C. A. Elvehjem, J. Biol. Chem. 167, 135 (1947). 

 *"" E. Roberts, F. Younger, and S. Frankel, J. Biol. Chem. 191, 277 (1951). 



