GROWTH FACTORS 111 



Pyridoxal is converted, in presence of adenosine triphos- 



CHO 



HO /\ CH2OPO3H2 

 phate, to the phosphate 



N 



which acts as the co -decarboxylase for the amino acid 

 decarboxylases for tyrosine, tysine, asparagine, arginine 

 and ghitamic acid (see p. 228). 



Riboflavin. — ^'HsOH Warburg and Cln^stian, in 



(HOH l^^2, showed that riboflavin 



j was an essential part of the 



CHOH " yellow " respiratory enzyme, 



('HOH which, together Avith Co- 



I enzymes I and II, is concerned 



y^2 in the carbohydrate metabolism 



CH N N of yeasts and bacteria (see 



/\/\^\,_ Chapter XII). It occurs in 



^^'f !! y y~^^ yeasts and those bacteria which 



CH3.C C C XH do not require it as a gTO^\i:h 



^CH^X^cf-0 ^^^^^^' ^^^^ ^^ many animal 

 ~ tissues. Since it was originally 

 isolated from milk it is sometimes known as lactoflavin. 

 It is a grov>i:.h factor for most lactic acid bacteria, pro- 

 pionic acid bacteria, streptococci, Thermobacterium and 

 Clostridium tetani. 



Its function seems, obviously, to be built into the 

 enzjmie by those organisms which cannot sjoithesise it 

 for themselves. 



Uracil.— XH— co Richardson showed that for the 



('o CH. anaerobic growth of Staphylo- 



I II coccus aureus on synthetic 



XH— CH media it was necessary to add 



uracil. It is a component of nucleic acids (see Chapter 



XVIII), and is, presumably, required for their synthesis 



under anaerobic conditions. Staph, aureus appears to be 



