HISTIDASE ACTIVITY OF THE HALOPHILIC ARCHAEBACTERIUM, HALOFERAX-VOLCANII

Haloferax volcanii, which can use histidine as a source of nitrogen, p roduces histidase when grown in the presence of histidine but produces little or none of this enzyme when grown in the presence of ammonia o r of ammonia plus histidine. Histidase in crude extracts was activated by NaCl but not by KCl and was more stable in low salt concentrations than most known enzymes of halophilic archaebacteria.