AMINO ACID DECARBOXYLASES OF PROTEUS MORGANII

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Abstract
Addition of L-histidine to the medium induces the adaptive formation of histidine decarboxylase after a lag period of 1-2 hrs. along with a linearly increased growth rate. The adaptive enzyme formation is the highest at pH 6 and proceeds at a half maximum rate at 10-3 [image] L-histidine. The adaptively formed enzyme shows its optimum pH at 6 and a Km (Michaelis constant) of 10-3 [image]. 8-Azaguanine inhibits the enzyme formation, but does not affect the cellular growth at all. During incubation of the cells with 8-azaguanine, a 0.2 portion of guanylic acid of cellular ribonucleic acid is replaced by 8-azaguanine, whereas the contents of ribo- and deoxyribo-nucleic acids remain normal.