Adenosine aminohydrolase from monkey brain: partial purification and some kinetic properties.

Adenosine aminohydrolase from monkey brain was purified ten fold. In pH 7.3 phosphate buffer at 37 degrees, this enzyme preparation deaminated adenosine and arabinosyladenine with apparent values for the Michaelis constant of 32 muM and 370 muM respectively. The products of both deamination reactions, i.e., inosine and arabinosylhypoxanthine, were competitive inhibitors with Ki equal to 220 muM and 1,000 muM, respectively. N6-benzyladenosine and 9-(1-hydroxy-2-octyl)adenine were competitive inhibitors and were more effective in inhibiting deamination of arabinosyladenine than of adenosine. It is suggested that these compounds might potentiate arabinosyladenine chemotherapy of neoplasms of the central nervous system.