X. EFFECTS OK DKl-'ICIENCY 279 



ov p>ii(l()\;il. I( will 1»(' appaiiMil I'loiii the pn'\i()us discussion thnt llic 

 pyri(l()\iiu*-}i;ro\\ii ('("lis \\(M'(' somewhat (Icliciciit in \ilaniiii Hr, ; llic rcciuiic- 

 nieiit for othcrwiso iion-cssential amino acids under these conditious is 

 excellent evidence that vitamin Br. is icciuired for their synthesis. Such 

 umiuo acids include cystine for /.. nist i\ L. arahinosus, and S. faecalia;^-^ 

 lysine, alanine, and threonine for />. ddbrucckii, L. arahinosus, and L. 

 casei;^^^ and threonine, lysine, alanine, serine, histidine, aspartic acid, 

 phenylalanine, and tyrosine for L. arabinosus.^'^^ In the presence but not in 

 the absence of ample vitamin Be , L. arahinosus also synthesizes trN^ptophan 

 from indole,"- and N. faccalis synthesizes histidine from imidazole pyruxic 

 acid.'*^ Indeed, each of the amino acids of casein must be present together 

 with D-alanine to permit growth of *S. faecalis in the absence of vitamin 

 Be .""* In the presence of ample vitamin Be , D-alanine and many of the 

 L-amino acids are synthesized by this organism. It thus appears that vita- 

 min Be is intimately invoh'ed in sjnithesis of each of the "non-essential" 

 amino acids in lactic acid bacteria; in their presence, the magnitude of the 

 \'itamin Be requirement falls either to zero or to such low levels that these 

 organisms can synthesize the small remaining amount re([uired. 



In the presence of adeciuate amounts of ^'itamin Be , many of the essential 

 amino acids for lactic acid bacteria can be replaced by the corresponding 

 keto or hydroxy acids; in the absence of the vitamin the keto and hydroxy 

 acids are without growth-promoting activity.'*'' It was shown that the keto 

 acids were transformed to amino acids by transamination; each of the trans- 

 aminases involved was vitamin Be-dependent and hence could not function 

 in the absence of supplies of this \itamin."^ 



Neurospora sitophila pyridoxineless requires approximately ten times as 

 much vitamin Be for growth in the absence of thiamine as is required when 

 thiamine is added. '■'■'' Vitamin Be-deficient cultures of this organism thus 

 require thiamine, which is synthesized when the supplies of vitamin Be 

 are more liberal. .Vlthough not so interpreted by the investigators, the 

 observation maj' indicate an important role for vitamin Be in the synthesis 

 of thiamine. A different type of relationship between these two vitamins oc- 

 curs in Saccharomijccs carlshergensis 4228 and in several similar yeasts"^' ^^^ 

 in which thiamine suppresses growth. This toxic effect is effectively coun- 



'32 B. S. Schweigert, J. Biol. Chem. 168, 283 (1947). 



1" H. P. Broquist and E. E. Snell, J. Biol. Chem. 180, 59 (1949). 



'3^ H. P. Bro(iuist and E. E. Snell, unpublished observations. 



'" J. T. Holden, R. H. Wildman, and K. E. Snell, J. Biol. Chem. 191, 559 (1951). 



'"» J. L. Stokes, .\. Larsen, C. K. Woodward, and J. W. Foster, ./. Biol. Chem. 150, 



17 (1943). 

 '»« A. S. Schultz and L. .\tkin, Arch. Biochem. 14, 369 (1947). 

 '" J. C. Rabinowitz and K. E. Snell, .\rch. Biochem. and Biophi/s. 33, 472 (1951). 



