抄録
Some of the kinetic properties of purified cytosine deaminase from Pseudomonas aureofaciens were studied.
The enzyme was activated by L-amino acids, especially by asparagine, aspartic acid and histidine, at the optimum pH of 10.0.
The enzyme was also activated by phosphate and pyrophosphate: 50% by 50 mm phosphate and 50% by 20mM pyrophosphate, while the enzyme was not affected by nucleotides and nucleosides. Some metal ions inhibited the enzyme reaction; especially Mn2+ and Cd2+ were observed to be effective inhibitors.
The apparent Michaelis constants Km for cytosine and 5-methylcytosine were found to be 4.5×10-3M and 5.7×10-4M, respectively. This enzyme was inhibited strongly by 1mM p-chloromercuribenzoate and seemed to be a thiol enzyme.
