0023-6152

AA00697606

22810

査読無

0023-6152

AA00697606

Some supplemental experiments were carried out on the activities specific for PAS and INAH as electron donor in the enzymatic reduction of NAD. Similarity was observed in inhibition by sodium azide, potassium cyanide, ethylenediaminetetraacetate and thiourea, although inhibition rate is more or less different. In addition, the enzymatic activity was not adsorbed on DEAE cellulose as urea and 4 dehydrogenases in the ammonia dehydrogenating system. However, clear evidence to show the difference was obtained in pH stability and influence of inorganic phosphate on the activity. The activity specific for PAS is most stable at pH 8 at 0°C for 60 minutes and enhanced by phosphate. On the other hand, maximum stability of the activity for INAH was observed at pH 7-7.5 and retarded by phosphate. These properties are different each other and from that of urea dehydrogenase which is most stable at pH 7.5 and activated by phosphate in a small amount but inhibited by it of higher quantity. Thus, the enzymes were proposed to be “PAS: NAD oxidoreductase” and “INAH: NAD oxidoreductase” or alternatively presumed to be dehydrogenases of PAS and I’NAH. These activities as well as dehydrogcnases of urea and GHA were demonstrated in several animal tissues such as cattle liver and liver, kidney and pancreas of rabbit, too.