III. BIOCHEMICAL SYSTEM 613 



convert pantothenic acid into its functional form, namely, CoA, the growth 

 effect of the CoA fragment indicates the lack of one of the enzymatic 

 reactions needed for the synthesis of CoA from free pantothenic acid. 

 The sluggish response of both Acetobacter suboxydans an Lactobacillus 

 bulgaricvs to pantothenic acid indicates a certain capacity for adaptive 

 formation of the lacking enzymatic step. 



1. Pantothenic Acid Conjugate of Cheldelin 



In the case of the Acetobacter suboxydans factor, Cheldelin showed that 

 it is destroyed by intestinal phosphatase.^^ It was found, subsequently, 

 that intact CoA as well as some of its fragments are active, and it was con- 

 firmed that intestinal phosphate destroys activity or reduces it to a low 

 level. During studies on the constitution of CoA, as already mentioned, 

 Novelli studied the Acetobacter factor in detail.^^ He found that, if the 

 organism had been grown on CoA, it would respond best to intact CoA. 

 But if it had been grown on partially decomposed CoA, it would respond 

 most actively to a phosphorylated fragment obtained by treatment with 

 potato dinucleotidase, by mild acid hydrolysis, or with an enzyme ob- 

 tained from snake venom. This Acetobacter factor has now been identified 

 as phospho-4-pantethine which was recently synthesized by Baddiley and 

 Thain and biologically tested in this laboratory.*^ 



Acetobacter is the only organism known so far which responds reasonably 

 well to all bound forms of pantothenic acid. This organism has frequently 

 been used in this laboratory for a qualitative detection of pantothenic 

 acid in all bound forms, e.g., in chromatograms of CoA fragments.^^ 



2. Pantethine (Lactobacillus bulgaricus Factor) 



In 1947, Williams et al.^^ discovered a new growth factor for Lactobacillus 

 bulgaricus. Snell et alP and Williams et al.^° independently observed that 

 large amounts of pantothenic acid would replace the factor. In their con- 

 centrates, pantothenic acid was found to be present in a bound form. As 

 mentioned already, Snell and his group compared this factor with CoA.*^ 

 They found that the intact coenzyme was inactive. But dephosphorylation 

 with intestinal phosphatase liberated a very active compound comparable 

 to their factor. On the other hand, treatment ^\dth liver enzyme completely 

 destroyed the activity of the LBF. This group of organisms, therefore, 

 seemed to be lacking in the enzyme which synthesizes the link to panto- 

 thenic acid, specifically hydrolyzed by the liver enzyme. This is now known 

 to be a peptidic link between pantothenic acid carboxyl and the amino 

 group of cysteamine. In summary, the anomaly in Lactobacillus bidgaricus 

 appears to be the lack of or slow adaptation to the enzymatic synthesis of 

 the link between thioethanolamine (or rather cysteine; cf. above) and the 

 carboxyl group of pantothenic acid. 



