136 S. S. COHEN 



tissues had fallen to 10 %, or less, of the normal content of these proteins in 

 the tissues. This would signify that the protein apoenzymes are less stable in 

 the absence of the prosthetic groups or that their rate of synthesis is dimin- 

 ished under these conditions. 



However, growth and polymer synthesis in general may contmue in the 

 absence of certain essential metabohtes, as has been discussed above in 

 sections of pathological growth and elsewhere. In most of these instances, the 

 control of the synthesis of particular polymers has been related to particular 

 metabohtes which they contain, e.g., diaminopimehc acid m cell wall syn- 

 thesis, or to the presence or absence of their controlling mechanism, e.g., the 

 maintenance of microsomal enzymes in the presence of the nucleus in Amoeba. 

 In some organisms, nutritional deficiencies with respect to a particular 

 metabolite have led to quite unusual growth patterns. 



When Proteus vulgaris is grown in a medium with hmiting concentrations 

 of nicotinic acid, essential for pyridine coenzyme production, and all other 

 requirements are supphed in excess, growth does not cease immediately after 

 the vitamin disappears from the medium. There is a linear phase of proto- 

 plasmic synthesis and Og consumption, apparently determined by the 

 temporarily fixed complement of pyridine coenzyme (Jackson and Copping, 

 1952). A comparable growth pattern has been observed for Mycobacterium 

 tuberculosis var. hominis in in vitro cultivation, indicating a deficiency in the 

 medium with respect to some essential metabohte stored earher in a previous 

 phase of growth (Fisher et al., 1951). 



When certain strains of Staphylococcus aureus are grown in fresh broth, 

 the hyaluronidase produced is proportional to the increment in mass of the 

 bacteria. However, the use of media partially deficient in thiamine or 

 nicotinic acid results in a lower ratio of this enzyme to the mass of the 

 organism (Eogers, 1957). Thus, the synthesis of specific polymers may be 

 more sensitive to vitamin deficiencies than the synthesis of all the bacterial 

 polymers in general. The presence of a-aminobutyric acid in cultures also 

 decreases the proportion of ceU protein which appears as hyaluronidase. 



A number of workers have studied effects of nutritional deficiencies in 

 plants on protein and enzymatic deficiencies. A sulfur deficiency in alfalfa, 

 for example, results in the decrease of methionine and cystine in plant 

 protein. However, the plant protein is now enriched with respect to aspara- 

 gine and arginine, of wliich the former accumulates earliest (Mertz et al., 

 1952). Thus, the protein composition of an intact organism appears far more 

 plastic than experiments with microorganisms would imply, when growth 

 stops in the absence of a required amino acid. 



Even more bizarre results were observed by Nason and collaborators, who 

 studied the effect of metal deficiencies on the growth of tomato plants. Fe 

 and Cu deficiencies produced marked drops in enzymes containing the 



