PANTOTHENIC ACID CONJUGATES AND GROWTH OF ACETOBACTER SUBOXYDANS

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Abstract
The activity of pantothenylcystine and pantethine but not that of pantothenic or pantoic acids in supporting growth of Acetobacter suboxydans, strain 621, in pantothenic acid-free medium is increased greatly by autoclaving with the medium or treatment with reducing agents. The max. observed activity is displayed by the mercuric mercaptides of pantothenylcysteine and of pantetheine. Only the -SH compounds, and not the -S-S-compounds, serve as growth factors. The activity of 4-phos-phopantethine and of coenzyme A also is increased greatly by reducing agents; under optimal conditions coenzyme A, 4[mu]-phosphopantetheine, pantetheine, and pantothenylcysteine show similar activities for this organism that are 7 to 12 times those of pantothenic or pantoic acids. The activities are thus in accord with the view that biosynthesis of coenzyme A proceeds successively through pantoate, pantothenate, pantothenylcysteine, pantetheine, and 4[image]-phosphopantetheine; all of the intermediates from pantothenylcysteine on show high activity for A. suboxydans when supplied in the reduced form or as appropriate disulfides that can be reduced by the organism. It is concluded that the A. suboxydans stimulatory factor of natural materials (pantothenic acid conjugate) is a mixture of such compounds.