Comparative studies on some ammonia-producing enzymes in the excretory organs of vertebrates

Abstract

1. 1. The activities of four enzymes: adenosine aminohydrolase, 5′-nucleotidase, AMP-aminohydrolase and glutaminase were investigated in the kidneys of fifteen vertebrate species and in the gills if carp. 2. 2. The kidneys of lower vertebrates like fish and amphibia are able to produce more ammonia from AMP than from glutamine. The same is true for carp's gills. 3. 3. Ammonia production by the kidneys of the tortoise and the hen runs at about the same rate from AMP of glutamine. 4. 4.In contrast to lower vertebrates, the kidneys of all mammals investigated are able to produce less ammonia from AMP than from glutamine. 5. 5. The localization of the enzymes decomposing adenylic acid and adenosine in the subcellular fractions of kidneys and gills is shown. 6. 6. The possible role of the AMP-aminohydrolase in the urinary ammonia formation in lower vertebrates is discussed.